diff --git a/.gitignore b/.gitignore
index 7770dd90..df27462f 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,3 +2,4 @@
 /cgcs-centos-repo
 /cgcs-tis-repo
 /cgcs-3rd-party-repo
+/local-build-data
diff --git a/build-data/build_avoidance_source b/build-data/build_avoidance_source
new file mode 100644
index 00000000..71135f20
--- /dev/null
+++ b/build-data/build_avoidance_source
@@ -0,0 +1,23 @@
+#
+# Copyright (c) 2018 Wind River Systems, Inc.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+
+#
+# What files and directories need to be copied
+#
+BUILD_AVOIDANCE_SRPM_DIRECTORIES="inputs srpm_assemble rpmbuild/SRPMS rpmbuild/SOURCES"
+BUILD_AVOIDANCE_SRPM_FILES=""
+BUILD_AVOIDANCE_RPM_DIRECTORIES="results rpmbuild/RPMS rpmbuild/SPECS"
+BUILD_AVOIDANCE_RPM_FILES=".platform_release"
+
+
+#
+# Copy the lines below to $MY_REPO/local-build-data/build_avoidance_source,
+# then uncomment and fill in the values giving the location of your local reference build.
+#
+# BUILD_AVOIDANCE_USR="jenkins"
+# BUILD_AVOIDANCE_HOST="machine.corp.com"
+# BUILD_AVOIDANCE_DIR="/localdisk/loadbuild/jenkins/StarlingX_Build"
diff --git a/build-tools/build-avoidance-utils.sh b/build-tools/build-avoidance-utils.sh
new file mode 100644
index 00000000..d728c760
--- /dev/null
+++ b/build-tools/build-avoidance-utils.sh
@@ -0,0 +1,842 @@
+#
+# Copyright (c) 2018 Wind River Systems, Inc.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+#
+# Functions related to build avoidance.
+#
+# Do not call directly.  Used by build-pkgs.
+#
+# Build avoidance downloads rpm, src.rpm and other artifacts of
+# build-pkgs for a local reference build.  The reference would
+# typically be an automated build run atleast daily.
+# The MY_WORKSPACE directory for the reference build shall have
+# a common root directory, and a leaf directory that is a time stamp
+# in a sortable parsable format.   Default YYYYMMDDThhmmssZ.
+#  e.g. /localdisk/loadbuild/jenkins/StarlingX/20180719T113021Z
+#
+# Other formats can be used by setting the following variables
+# in $MY_REPO/local-build-data/build_avoidance_source.
+#   e.g. to allow format YYYY-MM-DD_hh-mm-ss
+# BUILD_AVOIDANCE_DATE_FORMAT="%Y-%m-%d"
+# BUILD_AVOIDANCE_TIME_FORMAT="%H-%M-%S"
+# BUILD_AVOIDANCE_DATE_TIME_DELIM="_"
+# BUILD_AVOIDANCE_DATE_TIME_POSTFIX=""
+#
+# Note: Must be able to rsync and ssh to the machine that holds the
+# reference builds.
+#
+# In future alternative transfer protocols may be supported.
+# Select the alternate protocol by setting the following variables
+# in $MY_REPO/local-build-data/build_avoidance_source.
+# e.g.
+# BUILD_AVOIDANCE_FILE_TRANSFER="my-supported-prototcol"
+#
+
+BUILD_AVOIDANCE_USR=""
+BUILD_AVOIDANCE_HOST=""
+BUILD_AVOIDANCE_DIR=""
+BUILD_AVOIDANCE_URL=""
+
+# Default date/time format, iso-8601 compact, 20180912T143913Z
+# Syntax is a subset of that use by the unix 'date' command.
+BUILD_AVOIDANCE_DATE_FORMAT="%Y%m%d"
+BUILD_AVOIDANCE_TIME_FORMAT="%H%M%S"
+BUILD_AVOIDANCE_DATE_TIME_DELIM="T"
+BUILD_AVOIDANCE_DATE_TIME_POSTFIX="Z"
+
+# Default file transfer method
+BUILD_AVOIDANCE_FILE_TRANSFER="rsync"
+
+# Default is to use timestamps and days in UTC
+#
+# If you prefer local time, then set 'BUILD_AVOIDANCE_DATE_UTC=0'
+# in '$MY_REPO/local-build-data/build_avoidance_source'
+BUILD_AVOIDANCE_DATE_UTC=1
+
+BUILD_AVOIDANCE_DATA_DIR="$MY_WORKSPACE/build_avoidance_data"
+BUILD_AVOIDANCE_SOURCE="$MY_REPO/build-data/build_avoidance_source"
+BUILD_AVOIDANCE_LOCAL_SOURCE="$MY_REPO/local-build-data/build_avoidance_source"
+BUILD_AVOIDANCE_TEST_CONTEXT="$BUILD_AVOIDANCE_DATA_DIR/test_context"
+BUILD_AVOIDANCE_LAST_SYNC_FILE="$BUILD_AVOIDANCE_DATA_DIR/last_sync_context"
+
+if [ ! -f $BUILD_AVOIDANCE_SOURCE ]; then
+    echo "Couldn't read $BUILD_AVOIDANCE_SOURCE"
+    exit 1
+fi
+
+echo "Reading: $BUILD_AVOIDANCE_SOURCE"
+source $BUILD_AVOIDANCE_SOURCE
+
+if [ -f $BUILD_AVOIDANCE_LOCAL_SOURCE ]; then
+    echo "Reading: $BUILD_AVOIDANCE_LOCAL_SOURCE"
+    source $BUILD_AVOIDANCE_LOCAL_SOURCE
+fi
+
+UTC=""
+
+if [ $BUILD_AVOIDANCE_DATE_UTC -eq 1 ]; then
+    UTC="--utc"
+fi
+
+
+if [ "x$BUILD_AVOIDANCE_OVERRIDE_DIR" != "x" ]; then
+    BUILD_AVOIDANCE_DIR="$BUILD_AVOIDANCE_OVERRIDE_DIR"
+fi
+
+if [ "x$BUILD_AVOIDANCE_OVERRIDE_HOST" != "x" ]; then
+    BUILD_AVOIDANCE_HOST="$BUILD_AVOIDANCE_OVERRIDE_HOST"
+fi
+
+if [ "x$BUILD_AVOIDANCE_OVERRIDE_USR" != "x" ]; then
+    BUILD_AVOIDANCE_USR="$BUILD_AVOIDANCE_OVERRIDE_USR"
+fi
+
+echo "BUILD_AVOIDANCE_DIR=$BUILD_AVOIDANCE_DIR"
+echo "BUILD_AVOIDANCE_HOST=$BUILD_AVOIDANCE_HOST"
+echo "BUILD_AVOIDANCE_USR=$BUILD_AVOIDANCE_USR"
+
+build_avoidance_clean () {
+    if [ -f $BUILD_AVOIDANCE_LAST_SYNC_FILE ]; then
+        \rm -f -v "$BUILD_AVOIDANCE_LAST_SYNC_FILE"
+    fi
+}
+
+
+date_to_iso_8601 () {
+    local DATE="$1"
+    local CENTURY=""
+    local YEAR_IN_CENTURY="00"
+    local MONTH="01"
+    local DAY="01"
+    local DAY_OF_YEAR=""
+
+    CENTURY="$(date  '+%C')"
+
+    for x in $(echo "${BUILD_AVOIDANCE_DATE_FORMAT}" | tr ' ' '#' | sed 's/%%/#/g' | tr '%' ' ' ); do
+        # Consume format case options
+        case ${x:0:1} in
+            ^) x=${x:1};;
+            \#) x=${x:1};;
+            *) ;;
+        esac
+
+        # Process format
+        case $x in
+            Y*)  CENTURY=${DATE:0:2}; YEAR_IN_CENTURY=${DATE:2:2}; DATE=${DATE:4}; x=${x:1};;
+            0Y*) CENTURY=${DATE:0:2}; YEAR_IN_CENTURY=${DATE:2:2}; DATE=${DATE:4}; x=${x:2};;
+            _Y*) CENTURY=$(echo "${DATE:0:2}" | tr ' ' '0'); YEAR_IN_CENTURY=${DATE:2:2}; DATE=${DATE:4}; x=${x:2};;
+
+            y*)  YEAR_IN_CENTURY=${DATE:0:2}; DATE=${DATE:2}; x=${x:1};;
+            0y*) YEAR_IN_CENTURY=${DATE:0:2}; DATE=${DATE:2}; x=${x:2};;
+            _y*) YEAR_IN_CENTURY=$(echo "${DATE:0:2}" | tr ' ' '0'); DATE=${DATE:2}; x=${x:2};;
+
+            C*)  CENTURY=${DATE:0:2}; DATE=${DATE:2}; x=${x:1};;
+            0C*) CENTURY=${DATE:0:2}; DATE=${DATE:2}; x=${x:2};;
+            _C*) CENTURY=$(echo "${DATE:0:2}" | tr ' ' '0'); DATE=${DATE:2}; x=${x:2};;
+
+            m*)  MONTH=${DATE:0:2}; DATE=${DATE:2}; x=${x:1};;
+            0m*) MONTH=${DATE:0:2}; DATE=${DATE:2}; x=${x:2};;
+            _m*) MONTH=$(echo "${DATE:0:2}" | tr ' ' '0'); DATE=${DATE:2}; x=${x:2};;
+            e*)  MONTH=$(echo "${DATE:0:2}" | tr ' ' '0'); DATE=${DATE:2}; x=${x:1};;
+            0e*) MONTH=${DATE:0:2}; DATE=${DATE:2}; x=${x:2};;
+            _e*) MONTH=$(echo "${DATE:0:2}" | tr ' ' '0'); DATE=${DATE:2}; x=${x:2};;
+            b*)  MONTH="$(date -d "${DATE:0:3} 1 2000" '+%m')"; DATE=${DATE:3}; x=${x:1};;
+            h*)  MONTH="$(date -d "${DATE:0:3} 1 2000" '+%m')"; DATE=${DATE:3}; x=${x:1};;
+
+            d*)  DAY=${DATE:0:2}; DATE=${DATE:2}; x=${x:1};;
+            0d*) DAY=${DATE:0:2}; DATE=${DATE:2}; x=${x:2};;
+            _d*) DAY=$(echo "${DATE:0:2}" | tr ' ' '0'); DATE=${DATE:2}; x=${x:2};;
+
+            j*)  DAY_OF_YEAR=${DATE:0:3}; DATE=${DATE:3}; x=${x:1};;
+            0j*) DAY_OF_YEAR=${DATE:0:3}; DATE=${DATE:3}; x=${x:2};;
+            _j*) DAY_OF_YEAR=$(echo "${DATE:0:3}" | tr ' ' '0'); DATE=${DATE:3}; x=${x:2};;
+
+            D*) MONTH=${DATE:0:2}; DAY=${DATE:3:2}; YEAR_IN_CENTURY=${DATE:6:2}; DATE=${DATE:8}; x=${x:1};;
+            F*) CENTURY=${DATE:0:2}; YEAR_IN_CENTURY=${DATE:2:2}; MONTH=${DATE:5:2}; DAY=${DATE:8:2}; DATE=${DATE:10}; x=${x:1};;
+            *) >&2 echo "$FUNCNAME (${LINENO}): Unsupported date format: ${BUILD_AVOIDANCE_DATE_FORMAT}"; return 1;;
+        esac
+
+        # consume remaing non-interpreted content
+        if [ "$(echo "${DATE:0:${#x}}" |  tr ' ' '#')" != "${x}" ]; then
+            >&2 echo "$FUNCNAME (${LINENO}): Unexpected content '${DATE:0:${#x}}' does not match expected '${x}': '$1' being parsed vs '${BUILD_AVOIDANCE_DATE_FORMAT}'"
+            return 1
+        fi
+        DATE=${DATE:${#x}}
+    done
+
+    if [ "${DAY_OF_YEAR}" != "" ]; then
+        local YEAR_SEC
+        local DOY_SEC
+        YEAR_SEC="$(date -d "${CENTURY}${YEAR_IN_CENTURY}-01-01" '+%s')"
+        DOY_SEC=$((YEAR_SEC+(DAY_OF_YEAR-1)*24*60*60))
+        MONTH="$(date "@$DOY_SEC" "+%m")"
+        DAY="$(date "@$DOY_SEC" "+%d")"
+    fi
+
+    echo "${CENTURY}${YEAR_IN_CENTURY}-${MONTH}-${DAY}"
+    return 0
+}
+
+time_to_iso_8601 () {
+    TIME="$1"
+    local HOUR="00"
+    local H12=""
+    local AMPM=""
+    local MINUTE="00"
+    local SECOND="00"
+
+    CENTURY="$(date  '+%C')"
+
+    for x in $(echo "${BUILD_AVOIDANCE_TIME_FORMAT}" | tr ' ' '#' | sed 's/%%/#/g' | tr '%' ' ' ); do
+        # Consume format case options
+        case ${x:0:1} in
+            ^) x=${x:1};;
+            \#) x=${x:1};;
+            *) ;;
+        esac
+
+        # Process format
+        case $x in
+            H*)  HOUR=${TIME:0:2}; TIME=${TIME:2}; x=${x:1};;
+            0H*) HOUR=${TIME:0:2}; TIME=${TIME:2}; x=${x:2};;
+            _H*) HOUR="$(echo "${TIME:0:2}" | tr ' ' '0')"; TIME=${TIME:2}; x=${x:2};;
+            k*)  HOUR="$(echo "${TIME:0:2}" | tr ' ' '0')"; TIME=${TIME:2}; x=${x:1};;
+            0k*) HOUR=${TIME:0:2}; TIME=${TIME:2}; x=${x:2};;
+            _k*) HOUR="$(echo "${TIME:0:2}" | tr ' ' '0')"; TIME=${TIME:2}; x=${x:2};;
+
+            I*)  H12=${TIME:0:2}; TIME=${TIME:2}; x=${x:1};;
+            0I*) H12=${TIME:0:2}; TIME=${TIME:2}; x=${x:2};;
+            _I*) H12="$(echo "${TIME:0:2}" | tr ' ' '0')"; TIME=${TIME:2}; x=${x:2};;
+            l*)  H12="$(echo "${TIME:0:2}" | tr ' ' '0')"; TIME=${TIME:2}; x=${x:1};;
+            0l*) H12=${TIME:0:2}; TIME=${TIME:2}; x=${x:2};;
+            _l*) H12="$(echo "${TIME:0:2}" | tr ' ' '0')"; TIME=${TIME:2}; x=${x:2};;
+            p*) AMPM=${TIME:0:2}; TIME=${TIME:2}; x=${x:1};;
+
+            M*)  MINUTE=${TIME:0:2}; TIME=${TIME:2}; x=${x:1};;
+            0M*) MINUTE=${TIME:0:2}; TIME=${TIME:2}; x=${x:2};;
+            _M*) MINUTE="$(echo "${TIME:0:2}" | tr ' ' '0')"; TIME=${TIME:2}; x=${x:2};;
+
+            S*)  SECOND=${TIME:0:2}; TIME=${TIME:2}; x=${x:1};;
+            0S*) SECOND=${TIME:0:2}; TIME=${TIME:2}; x=${x:2};;
+            _S*) SECOND="$(echo "${TIME:0:2}" | tr ' ' '0')"; TIME=${TIME:2}; x=${x:2};;
+
+            R*) HOUR=${TIME:0:2}; MINUTE=${TIME:3:2} TIME=${TIME:5}; x=${x:1};;
+            r*) H12=${TIME:0:2}; MINUTE=${TIME:3:2}; SECOND=${TIME:6:2}; AMPM=${TIME:9:2}; TIME=${TIME:11}; x=${x:1};;
+            T*) HOUR=${TIME:0:2}; MINUTE=${TIME:3:2}; SECOND=${TIME:6:2}; TIME=${TIME:8}; x=${x:1};;
+
+            *) >&2 echo "$FUNCNAME (${LINENO}): Unsupported time format: ${BUILD_AVOIDANCE_TIME_FORMAT}"; return 1;;
+        esac
+
+        # consume remaing non-interpreted content
+        if [ "$(echo "${TIME:0:${#x}}" |  tr ' ' '#')" != "${x}" ]; then
+            >&2 echo "$FUNCNAME (${LINENO}): Unexpected content '${TIME:0:${#x}}' does not match expected '${x}': '$1' being parsed vs '${BUILD_AVOIDANCE_TIME_FORMAT}'"
+            return 1
+        fi
+        TIME=${TIME:${#x}}
+    done
+
+    if [ "$H12" != "" ] && [ "$AMPM" != "" ]; then
+        HOUR="$(date "$H12:01:01 $AMPM" '+%H')"
+    else
+        if [ "$H12" != "" ] && [ "$AMPM" != "" ]; then
+            >&2 echo "$FUNCNAME (${LINENO}): Unsupported time format: ${BUILD_AVOIDANCE_TIME_FORMAT}"
+            return 1
+        fi
+    fi
+
+    echo "${HOUR}:${MINUTE}:${SECOND}"
+    return 0
+}
+
+date_time_to_iso_8601 () {
+    local DATE_TIME="$1"
+    local DATE
+    local TIME
+    local DECODED_DATE
+    local DECODED_TIME
+    DATE=$(echo "${DATE_TIME}" | cut -d ${BUILD_AVOIDANCE_DATE_TIME_DELIM} -f 1)
+    TIME=$(echo "${DATE_TIME}" | cut -d ${BUILD_AVOIDANCE_DATE_TIME_DELIM} -f 2 | sed "s#${BUILD_AVOIDANCE_DATE_TIME_POSTFIX}\$##")
+    DECODED_DATE=$(date_to_iso_8601 "${DATE}")
+    DECODED_TIME=$(time_to_iso_8601 "${TIME}")
+    echo "${DECODED_DATE}T${DECODED_TIME}$(date $UTC '+%:z')"
+}
+
+#
+# test_build_avoidance_context <path-to-context-file>
+#
+# Is the provided context file compatible with the current
+# state of all of our gits?  A compatible context is one
+# where every commit in the context file is visible in our
+# current git history.
+#
+# Returns: Timestamp of context tested.
+# Exit code: 0 = Compatible
+#            1 = This context is older than the last applied
+#                build avoidance context.  If you are searching
+#                newest to oldest, you might as well stop.
+#            2 = Not compatible
+#
+test_build_avoidance_context () {
+    local context="$1"
+    local BA_LAST_SYNC_CONTEXT="$2"
+    local BA_CONTEXT=""
+
+    BA_CONTEXT=$(basename $context | cut -d '.' -f 1)
+    >&2 echo "test: $BA_CONTEXT"
+
+    if [ "$BA_CONTEXT" == "$BA_LAST_SYNC_CONTEXT" ]; then
+        # Stop the search.  We've reached the last sync point
+        BA_CONTEXT=""
+        echo "$BA_CONTEXT"
+        return 1
+    fi
+
+    git_test_context "$context"
+    result=$?
+    if [ $result -eq 0 ]; then
+        # found a new context !!!
+        echo "$BA_CONTEXT"
+        return 0
+    fi
+
+    # Continue the search
+    BA_CONTEXT=""
+    echo "$BA_CONTEXT"
+    return 2
+}
+
+
+#
+# get_build_avoidance_context
+#
+# Return URL of the most recent jenkins build that is compatable with
+# the current software context under $MY_REPO.
+#
+get_build_avoidance_context () {
+    (
+    local context
+    local BA_CONTEXT=""
+    local BA_LAST_SYNC_CONTEXT=""
+
+    # Load last synced context
+    if [ -f $BUILD_AVOIDANCE_LAST_SYNC_FILE ]; then
+        BA_LAST_SYNC_CONTEXT=$(head -n 1 $BUILD_AVOIDANCE_LAST_SYNC_FILE)
+    fi
+
+    mkdir -p $BUILD_AVOIDANCE_DATA_DIR
+    if [ $? -ne 0 ]; then
+        >&2 echo "Error: $FUNCNAME (${LINENO}): mkdir -p $BUILD_AVOIDANCE_DATA_DIR"
+        return 1
+    fi
+
+    local REMOTE_CTX_DIR="context"
+    local LOCAL_CTX_DIR="$BUILD_AVOIDANCE_DATA_DIR/context"
+
+    # First copy the directory containing all the context files for
+    # the reference builds.
+    >&2 echo "Download latest reference build contexts"
+
+    # Must set this prior to build_avoidance_copy_dir.
+    # The setting is not exported outside of the subshell.
+    BUILD_AVOIDANCE_URL="$BUILD_AVOIDANCE_HOST:$BUILD_AVOIDANCE_DIR"
+
+    build_avoidance_copy_dir "$REMOTE_CTX_DIR" "$LOCAL_CTX_DIR"
+    if [ $? -ne 0 ]; then
+        >&2 echo "Error: $FUNCNAME (${LINENO}): build_avoidance_copy_dir '$REMOTE_CTX_DIR' '$LOCAL_CTX_DIR'"
+        return 1
+    fi
+
+    # Search for a new context to sync
+    cd $MY_REPO
+
+    if [ "$BUILD_AVOIDANCE_DAY" == "" ]; then
+        # Normal case:
+        # Search all contexts, newest to oldest, for a good context.
+        for context in $(ls -1rd $LOCAL_CTX_DIR/*context); do
+            >&2 echo "context=$context"
+            BA_CONTEXT=$(test_build_avoidance_context $context $BA_LAST_SYNC_CONTEXT)
+            if [ $? -le 1 ]; then
+                # Stop search.  Might or might not have found a good context.
+                break;
+            fi
+        done
+    else
+        # Special case when a target day is specified.  Why would we do this?
+        # Reason is we might want the reference build to itself use build
+        # avoidance referencing prior builds of itself, except for one build
+        # a week when we use a full build rather than a build avoidance build.
+        #    e.g.   Sunday - full build
+        #           Mon-Sat - avoidance builds that refernce Sunday build.
+        #
+        # Starting from last <TARG_DAY> (e.g. "Sunday"), search newest to
+        # oldest for a good context.  If none found, increment the target
+        # day (e.g. Monday) and search again.  Keep incrementing until a
+        # good build is found, or target day + offset days would be a date
+        # in the furure.
+        #
+        local TARG_DAY=$BUILD_AVOIDANCE_DAY
+        local TODAY_DATE
+        local TODAY_DAY
+        local TARG_DATE=""
+        local TARG_TS
+        local TODAY_TS
+
+        TODAY_DATE=$(date  $UTC +%Y-%m-%d)
+        TODAY_DAY=$(date $UTC "+%A")
+
+        for OFFSET_DAYS in 0 1 2 3 4 5 6; do
+            if [ "$TARG_DAY" != "" ]; then
+                # Convert TARG_DAY+OFFSET_DAYS to TARG_DATE
+
+                if [ "$TODAY_DAY" == "$TARG_DAY" ]; then
+                    TARG_DATE=$(date $UTC -d"$TARG_DAY+$OFFSET_DAYS days" +%Y-%m-%d)
+                else
+                    TARG_DATE=$(date $UTC -d"last-$TARG_DAY+$OFFSET_DAYS days" +%Y-%m-%d)
+                fi
+                >&2 echo "TARG_DATE=$TARG_DATE"
+
+                TARG_TS=$(date $UTC -d "$TARG_DATE" +%s)
+                TODAY_TS=$(date $UTC -d "$TODAY_DATE" +%s)
+                if [ $TARG_TS -gt $TODAY_TS ]; then
+                    # Skip if offset has pushed us into future dates
+                    continue;
+                fi
+
+                if [ "$TARG_DATE" == "$TODAY_DATE" ]; then
+                    TARG_DATE=""
+                fi
+            fi
+
+            # Search build, newest to oldest, satisfying TARG_DATE
+            for f in $(ls -1rd $LOCAL_CTX_DIR/*context); do
+                DATE=$(date_to_iso_8601 $(basename "$f"))
+                if [ $? -ne 0 ]; then
+                    >&2 echo "Failed to extract date from filename '$(basename "$f")', ignoring file"
+                    continue
+                fi
+
+                >&2 echo "   DATE=$DATE, TARG_DATE=$TARG_DATE"
+
+                if [ "$DATE" == "$TARG_DATE" ] || [ "$TARG_DATE" == "" ] ; then
+                    context=$f;
+                else
+                    continue
+                fi
+
+                >&2 echo "context=$context"
+
+                BA_CONTEXT=$(test_build_avoidance_context $context $BA_LAST_SYNC_CONTEXT)
+
+                if [ $? -le 1 ]; then
+                    # Stop search.  Might or might not have found a good context.
+                    break;
+                fi
+            done
+
+            if [ "$BA_CONTEXT" != "" ]; then
+                # Found a good context.
+                break
+            fi
+        done
+    fi
+
+    if [ "$BA_CONTEXT" == "" ]; then
+        # No new context found
+        return 1
+    fi
+
+    # test that the reference build context hasn't been deleted
+    local BA_CONTEXT_DIR="$BUILD_AVOIDANCE_DIR/$BA_CONTEXT"
+    >&2 echo "ssh $BUILD_AVOIDANCE_HOST '[ -d $BA_CONTEXT_DIR ]'"
+    if ! ssh $BUILD_AVOIDANCE_HOST '[ -d $BA_CONTEXT_DIR ]' ; then
+        return 1
+    fi
+
+    # Save the latest context
+    >&2 echo "BA_CONTEXT=$BA_CONTEXT"
+    >&2 echo "BUILD_AVOIDANCE_LAST_SYNC_FILE=$BUILD_AVOIDANCE_LAST_SYNC_FILE"
+    echo $BA_CONTEXT > $BUILD_AVOIDANCE_LAST_SYNC_FILE
+
+    # The location of the load with the most compatable new context
+    URL=$BUILD_AVOIDANCE_HOST:$BA_CONTEXT_DIR
+
+    # return URL to caller.
+    echo $URL
+    return 0
+    )
+}
+
+
+#
+# build_avoidance_pre_clean <build-type>
+#
+# A place for any cleanup actions that must preceed a build avoidance build.
+#
+build_avoidance_pre_clean () {
+    local BUILD_TYPE="$1"
+
+    if [ "$BUILD_TYPE" == "" ]; then
+        >&2 echo "Error: $FUNCNAME (${LINENO}): BUILD_TYPE required"
+        return 1
+    fi
+
+    # clean prior builds
+    if [ -d $MY_WORKSPACE/$BUILD_TYPE ]; then
+        build-pkgs --clean --$BUILD_TYPE --no-build-avoidance
+        if [ $? -ne 0 ]; then
+            return 1
+        fi
+    fi
+
+    for f in $BUILD_AVOIDANCE_SRPM_FILES $BUILD_AVOIDANCE_RPM_FILES; do
+        if [ -f $MY_WORKSPACE/$BUILD_TYPE/$f ]; then
+            \rm -f $MY_WORKSPACE/$BUILD_TYPE/$f
+            if [ $? -ne 0 ]; then
+                >&2 echo "Error: $FUNCNAME (${LINENO}): rm -f $MY_WORKSPACE/$BUILD_TYPE/$f"
+                return 1
+            fi
+        fi
+    done
+
+    for d in $BUILD_AVOIDANCE_SRPM_DIRECTORIES $BUILD_AVOIDANCE_RPM_DIRECTORIES; do
+
+        if [ -d $MY_WORKSPACE/$BUILD_TYPE/$d ]; then
+            \rm -rf $MY_WORKSPACE/$BUILD_TYPE/$d
+            if [ $? -ne 0 ]; then
+                >&2 echo "Error: $FUNCNAME (${LINENO}): rm -rf $MY_WORKSPACE/$BUILD_TYPE/$d"
+                return 1
+            fi
+        fi
+    done
+
+    return 0
+}
+
+
+#
+# build_avoidance_copy_dir_rsync <remote-dir-path-rel> <local-dir-path> ['verbose']
+#
+# Copy a file from $BUILD_AVOIDANCE_URL/<remote-dir-path-rel>
+# to <local-dir-path> using rsync.
+#
+build_avoidance_copy_dir_rsync () {
+    local FROM="$1"
+    local TO="$2"
+    local VERBOSE="$3"
+    local FLAGS="-a -u"
+
+    if [ "$BUILD_AVOIDANCE_URL" == "" ]; then
+        >&2 echo "Error: $FUNCNAME (${LINENO}): BUILD_AVOIDANCE_URL no set"
+        return 1
+    fi
+    if [ "$VERBOSE" != "" ]; then
+        FLAGS="$FLAGS -v"
+        echo "rsync $FLAGS '$BUILD_AVOIDANCE_URL/$FROM/*' '$TO/'"
+    fi
+    rsync $FLAGS "$BUILD_AVOIDANCE_URL/$FROM/*" "$TO/"
+    return $?
+}
+
+#
+# build_avoidance_copy_file_rsync <remote-file-path-rel> <local-file-path> ['verbose']
+#
+# Copy a file from $BUILD_AVOIDANCE_URL/<remote-file-path-rel>
+# to <local-file-path> using rsync.
+#
+build_avoidance_copy_file_rsync () {
+    local FROM="$1"
+    local TO="$2"
+    local VERBOSE="$3"
+    local FLAGS="-a -u"
+
+    if [ "$BUILD_AVOIDANCE_URL" == "" ]; then
+        >&2 echo "Error: $FUNCNAME (${LINENO}): BUILD_AVOIDANCE_URL no set"
+        return 1
+    fi
+    if [ "$VERBOSE" != "" ]; then
+        FLAGS="$FLAGS -v"
+        echo "rsync $FLAGS '$BUILD_AVOIDANCE_URL/$FROM' '$TO'"
+    fi
+    rsync $FLAGS "$BUILD_AVOIDANCE_URL/$FROM" "$TO"
+    return $?
+}
+
+#
+# build_avoidance_copy_dir <remote-dir-path-rel> <local-dir-path> ['verbose']
+#
+# Copy a file from $BUILD_AVOIDANCE_URL/<remote-dir-path-rel>
+# to <local-dir-path>.  The copy method will be determined by
+# BUILD_AVOIDANCE_FILE_TRANSFER.  Only 'rsync' is supported at present.
+#
+# <local-dir-path> should be a directory,
+# mkdir -p will be called on <local-file-path>.
+#
+build_avoidance_copy_dir () {
+    local FROM="$1"
+    local TO="$2"
+    local VERBOSE="$3"
+
+    if [ "$VERBOSE" != "" ]; then
+        echo "mkdir -p '$TO'"
+    fi
+    mkdir -p "$TO"
+    if [ $? -ne 0 ]; then
+        >&2 echo "Error: $FUNCNAME (${LINENO}): mkdir -p $TO"
+        return 1
+    fi
+
+    case ${BUILD_AVOIDANCE_FILE_TRANSFER} in
+        rsync)
+            build_avoidance_copy_dir_rsync "$FROM" "$TO" "$VERBOSE"
+            return $?
+            ;;
+        *)
+            >&2 echo "Error: $FUNCNAME (${LINENO}): Unknown BUILD_AVOIDANCE_FILE_TRANSFER '${BUILD_AVOIDANCE_FILE_TRANSFER}'"
+            return 1
+            ;;
+    esac
+    return 1
+}
+
+#
+# build_avoidance_copy_file <remote-file-path-rel> <local-file-path> ['verbose']
+#
+# Copy a file from $BUILD_AVOIDANCE_URL/<remote-file-path-rel>
+# to <local-file-path>.  The copy method will be determined by
+# BUILD_AVOIDANCE_FILE_TRANSFER.  Only 'rsync' is supported at present.
+#
+# <local-file-path> should be a file, not a directory,
+# mkdir -p will be called on $(dirname <local-file-path>)
+#
+build_avoidance_copy_file () {
+    local FROM="$1"
+    local TO="$2"
+    local VERBOSE="$3"
+
+    if [ "$VERBOSE" != "" ]; then
+        echo "mkdir -p $(dirname '$TO')"
+    fi
+    mkdir -p "$(dirname "$TO")"
+    if [ $? -ne 0 ]; then
+        >&2 echo "Error: $FUNCNAME (${LINENO}): mkdir -p $(dirname "$TO")"
+        return 1
+    fi
+
+    case ${BUILD_AVOIDANCE_FILE_TRANSFER} in
+        rsync)
+            build_avoidance_copy_file_rsync "$FROM" "$TO" "$VERBOSE"
+            return $?
+            ;;
+        *)
+            >&2 echo "Error: $FUNCNAME (${LINENO}): Unknown BUILD_AVOIDANCE_FILE_TRANSFER '${BUILD_AVOIDANCE_FILE_TRANSFER}'"
+            return 1
+            ;;
+    esac
+    return 1
+}
+
+#
+# build_avoidance_copy <build-type> ['verbose']
+#
+# Copy the needed build artifacts for <build-type> from $BUILD_AVOIDANCE_URL.
+#
+build_avoidance_copy () {
+    local BUILD_TYPE="$1"
+    local VERBOSE="$2"
+
+    if [ "$BUILD_TYPE" == "" ]; then
+        >&2 echo "Error: $FUNCNAME (${LINENO}): BUILD_TYPE required"
+        return 1
+    fi
+
+    # Iterate through list of directories to copy
+    for d in $BUILD_AVOIDANCE_SRPM_DIRECTORIES $BUILD_AVOIDANCE_RPM_DIRECTORIES; do
+        build_avoidance_copy_dir "$BUILD_TYPE/$d" "$MY_WORKSPACE/$BUILD_TYPE/$d" "$VERBOSE"
+        if [ $? -ne 0 ]; then
+            >&2 echo "Error: $FUNCNAME (${LINENO}): build_avoidance_copy_dir '$BUILD_TYPE/$d' '$MY_WORKSPACE/$BUILD_TYPE/$d'"
+            return 1
+        fi
+    done
+
+    # Iterate through list of files to copy
+    for f in $BUILD_AVOIDANCE_SRPM_FILES $BUILD_AVOIDANCE_RPM_FILES; do
+        build_avoidance_copy_file "$BUILD_TYPE/$f" "$MY_WORKSPACE/$BUILD_TYPE/$f" "$VERBOSE"
+        if [ $? -ne 0 ]; then
+            >&2 echo "Error: $FUNCNAME (${LINENO}): build_avoidance_copy_file '$BUILD_TYPE/$f' '$MY_WORKSPACE/$BUILD_TYPE/$f'"
+            return 1
+        fi
+    done
+
+    return 0
+}
+
+#
+# build_avoidance_fixups <build-type>
+#
+# Fix paths in the build artifacts that we coppied that contain
+# the user name.
+#
+# Also, our credentials may differ from the reference build,
+# so substitute unsigned packages in place of signed packages.
+#
+build_avoidance_fixups () {
+    local BUILD_TYPE="$1"
+
+    local BA_SOURCE_BUILD_ENVIRONMENT
+    BA_SOURCE_BUILD_ENVIRONMENT="${BUILD_AVOIDANCE_USR}-$(basename $(dirname $BUILD_AVOIDANCE_URL))-$(basename $BUILD_AVOIDANCE_URL)-${SRC_BUILD_ENVIRONMENT}"
+    local RESULT_DIR=""
+    local FROM_DIR=""
+    local TO_DIR=""
+    local rpm_path_post_signing
+    local rpm_path_pre_signing
+    local rpm_name
+    local md5sum_post_signing
+    local md5sum_pre_signing
+
+    if [ "$BUILD_TYPE" == "" ]; then
+        >&2 echo "Error: $FUNCNAME (${LINENO}): BUILD_TYPE required"
+        return 1
+    fi
+
+    RESULT_DIR="$MY_WORKSPACE/$BUILD_TYPE/results"
+    FROM_DIR="${RESULT_DIR}/${BA_SOURCE_BUILD_ENVIRONMENT}-${BUILD_TYPE}"
+    TO_DIR="${RESULT_DIR}/${MY_BUILD_ENVIRONMENT}-${BUILD_TYPE}"
+    echo "$FUNCNAME: FROM_DIR=$FROM_DIR"
+    echo "$FUNCNAME: TO_DIR=$TO_DIR"
+    echo "$FUNCNAME: MY_BUILD_ENVIRONMENT=$MY_BUILD_ENVIRONMENT"
+
+    # Fix patchs the use MY_BUILD_ENVIRONMENT
+    if [ ! -d "$FROM_DIR" ]; then
+        >&2 echo "Error: $FUNCNAME (${LINENO}): Expected directory '$FROM_DIR' is missing."
+        return 1
+    fi
+
+    echo "$FUNCNAME: mv '$FROM_DIR' '$TO_DIR'"
+    \mv "$FROM_DIR" "$TO_DIR"
+    if [ $? -ne 0 ]; then
+        >&2 echo "Error: $FUNCNAME (${LINENO}): mv '$FROM_DIR' '$TO_DIR'"
+        return 1
+    fi
+
+    local MY_WS_BT="$MY_WORKSPACE/$BUILD_TYPE"
+
+    # Replace signed rpms with non-signed copies .... we aren't a formal build
+    for rpm_path_post_signing in $(find $MY_WS_BT/rpmbuild/RPMS -type f -name '*.rpm' | grep -v src.rpm); do
+
+        rpm_name=$(basename $rpm_path_post_signing)
+        rpm_path_pre_signing=$(find $MY_WS_BT/results -name $b | head -n1)
+        if [ "$rpm_path_pre_signing" != "" ]; then
+            md5sum_post_signing=$(md5sum ${rpm_path_post_signing} | cut -d ' ' -f 1)
+            md5sum_pre_signing=$(md5sum ${rpm_path_pre_signing} | cut -d ' ' -f 1)
+            if [ "${md5sum_post_signing}" != "${md5sum_pre_signing}" ]; then
+                echo "$FUNCNAME: fixing $rpm_name"
+                \rm -f ${rpm_path_post_signing}
+                if [ $? -ne 0 ]; then
+                    >&2 echo "Error: $FUNCNAME (${LINENO}): rm -f ${rpm_path_post_signing}"
+                    return 1
+                fi
+
+                \cp ${rpm_path_pre_signing} ${rpm_path_post_signing}
+                if [ $? -ne 0 ]; then
+                    >&2 echo "Error: $FUNCNAME (${LINENO}): cp ${rpm_path_pre_signing} ${rpm_path_post_signing}"
+                    return 1
+                fi
+            fi
+        fi;
+    done
+
+    return 0
+}
+
+
+#
+# build_avoidance <build-type>
+#
+# Look for a reference build that is applicable to our current git context.
+# and copy it to our local workspace, if we haven't already done so.
+#
+build_avoidance () {
+    local BUILD_TYPE="$1"
+
+    echo "==== Build Avoidance Start ===="
+
+    if [ "$BUILD_TYPE" == "" ]; then
+        >&2 echo "Error: $FUNCNAME (${LINENO}): BUILD_TYPE required"
+        return 1
+    fi
+
+    if [ "$BUILD_TYPE" == "installer" ]; then
+        >&2 echo "build_avoidance: BUILD_TYPE==installer not supported"
+        return 1
+    fi
+
+    build_avoidance_pre_clean $BUILD_TYPE
+    if [ $? -ne 0 ]; then
+        >&2 echo "Error: $FUNCNAME (${LINENO}): build_avoidance_pre_clean $BUILD_TYPE"
+        return 1
+    fi
+
+    build_avoidance_copy $BUILD_TYPE 'verbose'
+    if [ $? -ne 0 ]; then
+        >&2 echo "Error: $FUNCNAME (${LINENO}): build_avoidance_copy $BUILD_TYPE"
+        return 1
+    fi
+
+    build_avoidance_fixups $BUILD_TYPE
+    if [ $? -ne 0 ]; then
+        >&2 echo "Error: $FUNCNAME (${LINENO}): build_avoidance_fixups $BUILD_TYPE"
+        return 1
+    fi
+
+    echo "==== Build Avoidance Complete ===="
+    return 0
+}
+
+#
+# build_avoidance_save_reference_context
+#
+# For use by a reference build.  Copy the 'CONTEXT' file
+# from the build into a central directory where we save
+# the context of old builds.
+#
+# Individual reference builds use:
+#     MY_WORKSPACE=<common-dir>/<timestamp>
+# and context files are collected in dir:
+#     DEST_CTX_DIR=<common-dir>/context
+# using name:
+#     DEST_CTX=<timestamp>.context
+
+build_avoidance_save_reference_context () {
+    local DIR
+    DIR=$(dirname "${MY_WORKSPACE}")
+
+    # Note: SUB_DIR should be a timestamp
+    local SUB_DIR
+    SUB_DIR=$(basename "${MY_WORKSPACE}")
+
+    local SRC_CTX="${MY_WORKSPACE}/CONTEXT"
+    local DEST_CTX_DIR="${DIR}/context"
+    local DEST_CTX="${DEST_CTX_DIR}/${SUB_DIR}.context"
+
+    if [ ! -f "${SRC_CTX}" ]; then
+        echo "Context file not found at '${SRC_CTX}'"
+        return 1
+    fi
+
+    mkdir -p "${DEST_CTX_DIR}"
+    if [ $? -ne 0 ]; then
+        echo "Error: $FUNCNAME (${LINENO}): Failed to create directory '${DEST_CTX_DIR}'"
+        return 1
+    fi
+
+    cp "${SRC_CTX}" "${DEST_CTX}"
+    if [ $? -ne 0 ]; then
+        echo "Error: $FUNCNAME (${LINENO}): Failed to copy ${SRC_CTX} -> ${DEST_CTX}"
+        return 1
+    fi
+
+    return 0
+}
diff --git a/build-tools/build-pkgs b/build-tools/build-pkgs
index 9def3b01..15f7dd93 100755
--- a/build-tools/build-pkgs
+++ b/build-tools/build-pkgs
@@ -6,6 +6,9 @@
 # SPDX-License-Identifier: Apache-2.0
 #
 
+#
+# Build first src.rpms, then rpms, from source, or from a downloaded tarball
+# or src.rpm plus our additional patches.
 #
 # This program is a wrapper around build-pkgs-parallel and build-pkgs-serial
 #
diff --git a/build-tools/build-pkgs-parallel b/build-tools/build-pkgs-parallel
index 02360ac0..7d7bb2cc 100755
--- a/build-tools/build-pkgs-parallel
+++ b/build-tools/build-pkgs-parallel
@@ -1,10 +1,22 @@
 #!/bin/bash
 
+#
+# Copyright (c) 2018 Wind River Systems, Inc.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+#
+# Build first src.rpms, then rpms, from source, or from a downloaded tarball
+# or src.rpm plus our additional patches.
+#
 # This program is a wrapper around build-srpms-parallel and build-rpms-parallel
+#
 
 BUILD_PKGS_PARALLEL_DIR="$(dirname "$(readlink -f "${BASH_SOURCE[0]}" )" )"
 
 source "${BUILD_PKGS_PARALLEL_DIR}/git-utils.sh"
+source "${BUILD_PKGS_PARALLEL_DIR}/build-avoidance-utils.sh"
 source "${BUILD_PKGS_PARALLEL_DIR}/spec-utils"
 
 
@@ -13,14 +25,15 @@ usage () {
     echo "Usage: "
     echo "   Create source and Binary rpms:"
     echo "   Build optimizations (--no-descendants, --no-required, --no-build-info,"
-    echo "   --no-autoclean) are not recommended for the first build after a clone/pull,"
-    echo "   nor the final build prior to creating an iso or patch, but can be used"
-    echo "   for intermediate builds.  i.e. while debugging compilation failures." 
-    echo "      build-pkgs-parallel [--no-descendants] [--no-required] [--no-build-info] [--no-autoclean] [--careful] [--formal] [ list of package names ]"
+    echo "   --no-autoclean, --no-build-avoidance) are not recommended for the first build"
+    echo "   after a clone/pull, nor the final build prior to creating an iso or patch,"
+    echo "   but can be used for intermediate builds."
+    echo "   i.e. while debugging compilation failures."
+    echo "      build-pkgs-parallel [--build-avoidance | --no-build-avoidance] [--no-descendants] [--no-required] [--no-build-info] [--no-autoclean] [--careful] [--formal] [ list of package names ]"
     echo ""
     echo "   Delete source rpms, and the directories associated with it's creation:"
     echo "   Note: does not clean an edit environment"
-    echo "      build-pkgs-parallel --clean [ list of package names ]"
+    echo "      build-pkgs-parallel --clean [--build-avoidance | --no-build-avoidance] [ list of package names ]"
     echo ""
     echo "   Extract an src.rpm into a pair of git trees to aid in editing it's contents,"
     echo "   one for source code and one for metadata such as the spec file."
@@ -39,15 +52,20 @@ usage () {
 HELP=0
 CLEAN_FLAG=0
 EDIT_FLAG=0
+APPEND_LOG_FLAG=0
+BUILD_AVOIDANCE_FLAG=0
 STD_BUILD=1
 RT_BUILD=1
 INSTALLER_BUILD=0
 
+export BUILD_AVOIDANCE_URL=""
+
+
 # read the options
-TEMP=$(getopt -o h --long parallel,rt,std,installer,edit,no-meta-patch,no-descendants,no-required,no-build-info,no-autoclean,formal,careful,help,clean -n 'build-pkgs-parallel' -- "$@")
+TEMP=$(getopt -o h --long parallel,rt,std,installer,edit,build-avoidance,no-build-avoidance,build-avoidance-dir:,build-avoidance-host:,build-avoidance-user:,build-avoidance-day:,no-meta-patch,no-descendants,no-required,no-build-info,no-autoclean,formal,careful,help,clean,append-log -n 'build-pkgs-parallel' -- "$@")
 if [ $? -ne 0 ]; then
     usage
-    exit 0
+    exit 1
 fi
 eval set -- "$TEMP"
 
@@ -55,8 +73,21 @@ eval set -- "$TEMP"
 EXTRA_ARGS_COMMON=""
 EXTRA_ARGS_SRPM=""
 EXTRA_ARGS_RPM=""
+
+export BUILD_AVOIDANCE_OVERRIDE_DIR=""
+export BUILD_AVOIDANCE_OVERRIDE_HOST=""
+export BUILD_AVOIDANCE_OVERRIDE_USR=""
+export BUILD_AVOIDANCE_DAY=""
+
 while true ; do
     case "$1" in
+        --append-log)     APPEND_LOG_FLAG=1 ; shift ;;
+        --build-avoidance) BUILD_AVOIDANCE_FLAG=1 ; shift ;;
+        --no-build-avoidance) BUILD_AVOIDANCE_FLAG=0 ; shift ;;
+        --build-avoidance-dir)  BUILD_AVOIDANCE_OVERRIDE_DIR=$2; shift 2 ;;
+        --build-avoidance-host)  BUILD_AVOIDANCE_OVERRIDE_HOST=$2; shift 2 ;;
+        --build-avoidance-user)  BUILD_AVOIDANCE_OVERRIDE_USR=$2; shift 2 ;;
+        --build-avoidance-day) BUILD_AVOIDANCE_DAY=$2; shift 2 ;;
         --no-descendants) EXTRA_ARGS_COMMON+=" --no-descendants" ; shift ;;
         --formal)         EXTRA_ARGS_COMMON+=" --formal" ; shift ;;
         --careful)        EXTRA_ARGS_RPM+=" --careful" ; shift ;;
@@ -125,11 +156,15 @@ trap my_sighup HUP
 trap my_sigabrt ABRT
 trap my_sigterm TERM
 
+# Note: For ease of parsing, a TARGETS list always begins and ends 
+# with a space.  An empty target list consistes of two spaces.
 TARGETS=" $@ "
-TARGETS_STD=" "
-TARGETS_RT=" "
-TARGETS_INSTALLER=" "
-TARGETS_MISC=" "
+EMPTY_TARGETS="  "
+
+TARGETS_STD="$EMPTY_TARGETS"
+TARGETS_RT="$EMPTY_TARGETS"
+TARGETS_INSTALLER="$EMPTY_TARGETS"
+TARGETS_MISC="$EMPTY_TARGETS"
 
 find_targets () {
    local centos_pkg_dirs=$1
@@ -199,14 +234,28 @@ find_targets () {
       fi
    done
 
-   echo "$RESULT"
+   if [ "$RESULT" == " " ]; then
+       echo "$EMPTY_LIST"
+   else
+       echo "$RESULT"
+   fi
    return 0
 }
 
+if [ $EDIT_FLAG -eq 1 ] || [ "$TARGETS" != "$EMPTY_TARGETS" ]; then
+   BUILD_AVOIDANCE_FLAG=0
+fi
+
+echo "BUILD_AVOIDANCE_FLAG=$BUILD_AVOIDANCE_FLAG"
 echo "CLEAN_FLAG=$CLEAN_FLAG"
 echo "EDIT_FLAG=$EDIT_FLAG"
 
-if [ "x$TARGETS" != "x  " ]; then
+if [ $BUILD_AVOIDANCE_FLAG -eq 1 ]; then
+    # Build Avoidance requested. Get URL of a usable context, if any.
+    export BUILD_AVOIDANCE_URL=$(get_build_avoidance_context)
+fi
+
+if [ "$TARGETS" != "$EMPTY_TARGETS" ]; then
    TARGETS_STD="$(find_targets centos_pkg_dirs)"
 
    BUILD_TYPE_SAVE="$BUILD_TYPE"
@@ -247,44 +296,50 @@ echo "EXTRA_ARGS_RPM='$EXTRA_ARGS_RPM'"
 echo "TARGETS='$TARGETS'"
 echo "TARGETS_STD='$TARGETS_STD'"
 echo "TARGETS_RT='$TARGETS_RT'"
+echo "TARGETS_INSTALLER='$TARGETS_INSTALLER'"
 echo "TARGETS_MISC='$TARGETS_MISC'"
 
 if [ $CLEAN_FLAG -eq 1 ]; then
+
+   if [ "$TARGETS" == "$EMPTY_TARGETS" ] && [ $BUILD_AVOIDANCE_FLAG -eq 1 ] ; then
+      build_avoidance_clean
+   fi
+
    if [ $STD_BUILD -eq 1 ]; then
-      if [ "x$TARGETS" == "x  " ] || [ "$TARGETS_STD" != " " ] || [ "$TARGETS_MISC" != " " ]; then
+      if [ "$TARGETS" == "$EMPTY_TARGETS" ] || [ "$TARGETS_STD" != "$EMPTY_TARGETS" ] || [ "$TARGETS_MISC" != "$EMPTY_TARGETS" ]; then
          if [ $EDIT_FLAG -ne 1 ]; then
             echo "${BUILD_PKGS_PARALLEL_DIR}/build-rpms-parallel --std --clean $EXTRA_ARGS_COMMON $EXTRA_ARGS_RPM $TARGETS_STD $TARGETS_MISC"
             ${BUILD_PKGS_PARALLEL_DIR}/build-rpms-parallel --std --clean $EXTRA_ARGS_COMMON $EXTRA_ARGS_RPM $TARGETS_STD $TARGETS_MISC || exit 1
 
          fi
       fi
-      if [ "x$TARGETS" == "x  " ] || [ "$TARGETS_STD" != " " ] || [ "$TARGETS_MISC" != " " ]; then
+      if [ "$TARGETS" == "$EMPTY_TARGETS" ] || [ "$TARGETS_STD" != "$EMPTY_TARGETS" ] || [ "$TARGETS_MISC" != "$EMPTY_TARGETS" ]; then
          echo "${BUILD_PKGS_PARALLEL_DIR}/build-srpms-parallel --std --clean $EXTRA_ARGS_COMMON $EXTRA_ARGS_SRPM $TARGETS_STD $TARGETS_MISC"
          ${BUILD_PKGS_PARALLEL_DIR}/build-srpms-parallel --std --clean $EXTRA_ARGS_COMMON $EXTRA_ARGS_SRPM $TARGETS_STD $TARGETS_MISC || exit 1
       fi
    fi
 
    if [ $RT_BUILD -eq 1 ]; then
-      if [ "x$TARGETS" == "x  " ] || [ "$TARGETS_RT" != " " ] || [ "$TARGETS_MISC" != " " ]; then
+      if [ "$TARGETS" == "$EMPTY_TARGETS" ] || [ "$TARGETS_RT" != "$EMPTY_TARGETS" ] || [ "$TARGETS_MISC" != "$EMPTY_TARGETS" ]; then
          if [ $EDIT_FLAG -ne 1 ]; then
             echo "${BUILD_PKGS_PARALLEL_DIR}/build-rpms-parallel --rt --clean $EXTRA_ARGS_COMMON $EXTRA_ARGS_RPM $TARGETS_RT $TARGETS_MISC"
             ${BUILD_PKGS_PARALLEL_DIR}/build-rpms-parallel --rt --clean $EXTRA_ARGS_COMMON $EXTRA_ARGS_RPM $TARGETS_RT $TARGETS_MISC || exit 1
          fi
       fi
-      if [ "x$TARGETS" == "x  " ] || [ "$TARGETS_RT" != " " ] || [ "$TARGETS_MISC" != " " ]; then
+      if [ "$TARGETS" == "$EMPTY_TARGETS" ] || [ "$TARGETS_RT" != "$EMPTY_TARGETS" ] || [ "$TARGETS_MISC" != "$EMPTY_TARGETS" ]; then
          echo "${BUILD_PKGS_PARALLEL_DIR}/build-srpms-parallel --rt --clean $EXTRA_ARGS_COMMON $EXTRA_ARGS_SRPM $TARGETS_RT $TARGETS_MISC"
          ${BUILD_PKGS_PARALLEL_DIR}/build-srpms-parallel --rt --clean $EXTRA_ARGS_COMMON $EXTRA_ARGS_SRPM $TARGETS_RT $TARGETS_MISC || exit 1
       fi
    fi
 
    if [ $INSTALLER_BUILD -eq 1 ]; then
-      if [ "x$TARGETS" == "x" ] || [ "$TARGETS_INSTALLER" != " " ]; then
+      if [ "$TARGETS" == "$EMPTY_TARGETS" ] || [ "$TARGETS_INSTALLER" != "$EMPTY_TARGETS" ]; then
          if [ $EDIT_FLAG -ne 1 ]; then
             echo "${BUILD_PKGS_PARALLEL_DIR}/build-rpms-serial --installer --clean $EXTRA_ARGS_COMMON $EXTRA_ARGS_RPM $TARGETS_INSTALLER"
             ${BUILD_PKGS_PARALLEL_DIR}/build-rpms-serial --installer --clean $EXTRA_ARGS_COMMON $EXTRA_ARGS_RPM $TARGETS_INSTALLER || exit 1
          fi
       fi
-      if [ "x$TARGETS" == "x  " ] || [ "$TARGETS_INSTALLER" != " " ]; then
+      if [ "$TARGETS" == "$EMPTY_TARGETS" ] || [ "$TARGETS_INSTALLER" != "$EMPTY_TARGETS" ]; then
          echo "${BUILD_PKGS_PARALLEL_DIR}/build-srpms-serial --installer --clean $EXTRA_ARGS_COMMON $EXTRA_ARGS_SRPM $TARGETS_INSTALLER"
          ${BUILD_PKGS_PARALLEL_DIR}/build-srpms-serial --installer --clean $EXTRA_ARGS_COMMON $EXTRA_ARGS_SRPM $TARGETS_INSTALLER || exit 1
       fi
@@ -317,13 +372,22 @@ function launch_build()
    fi
 
    echo "Launching $build_type build, logging to $logfile"
-   \rm $logfile
+   if [ $APPEND_LOG_FLAG -eq 0 ] && [ -f $logfile ]; then
+       \rm $logfile
+   fi
+
 
    echo -e "\n######## $(date): Launching build-srpms-parallel --$build_type $EXTRA_ARGS $@\n" | tee --append $logfile
+
+   echo "BUILD_AVOIDANCE_URL=$BUILD_AVOIDANCE_URL" | tee --append $logfile
+   if [ "x$BUILD_AVOIDANCE_URL" != "x" ]; then
+      echo "build_avoidance $build_type" | tee --append $logfile
+      build_avoidance $build_type 2>&1 | tee --append $logfile
+   fi
+
    # No clean flag, call build-srpms-parallel followed by build-rpms-parallel
    echo "${BUILD_PKGS_PARALLEL_DIR}/build-srpms-parallel --$build_type $EXTRA_ARGS_COMMON $EXTRA_ARGS_SRPM $targets" | tee --append $logfile
    ${BUILD_PKGS_PARALLEL_DIR}/build-srpms-parallel --$build_type $EXTRA_ARGS_COMMON $EXTRA_ARGS_SRPM $targets 2>&1 | tee --append $logfile
-
    rc=${PIPESTATUS[0]}
    if [ $rc -eq 0 ]; then
       echo -e "\n######## $(date): build-srpm-parallel --$build_type was successful" | tee --append $logfile
@@ -371,19 +435,18 @@ fi
 echo "Capture build context"
 git_context > "${MY_WORKSPACE}/CONTEXT"
 
-
 if [ $STD_BUILD -eq 1 ]; then
-   if [ "x$TARGETS" == "x  " ] || [ "$TARGETS_STD" != " " ] || [ "$TARGETS_MISC" != " " ]; then
+   if [ "$TARGETS" == "$EMPTY_TARGETS" ] || [ "$TARGETS_STD" != "$EMPTY_TARGETS" ] || [ "$TARGETS_MISC" != "$EMPTY_TARGETS" ]; then
       launch_build std
    else
-      echo "Skipping 'std' build, no valid targets in list: $TARGETS"
+      echo "Skipping 'std' build, no valid targets in list: '$TARGETS'"
    fi
 else
    echo "Skipping 'std' build"
 fi
 
 if [ $RT_BUILD -eq 1 ]; then
-   if [ "x$TARGETS" == "x  " ] || [ "$TARGETS_RT" != " " ] || [ "$TARGETS_MISC" != " " ]; then
+   if [ "$TARGETS" == "$EMPTY_TARGETS" ] || [ "$TARGETS_RT" != "$EMPTY_TARGETS" ] || [ "$TARGETS_MISC" != "$EMPTY_TARGETS" ]; then
       launch_build rt
    else
       echo "Skipping 'rt' build, no valid targets in list: $TARGETS"
@@ -393,7 +456,7 @@ else
 fi
 
 if [ $INSTALLER_BUILD -eq 1 ]; then
-   if [ "x$TARGETS" == "x  " ] || [ "$TARGETS_INSTALLER" != " " ] || [ "$TARGETS_MISC" != " " ]; then
+   if [ "$TARGETS" == "$EMPTY_TARGETS" ] || [ "$TARGETS_INSTALLER" != "$EMPTY_TARGETS" ] || [ "$TARGETS_MISC" != "$EMPTY_TARGETS" ]; then
       launch_build installer
    else
       echo "Skipping 'installer' build, no valid targets in list: $TARGETS"
@@ -402,6 +465,15 @@ else
    echo "Skipping 'installer' build"
 fi
 
+# Make sure REFERENCE_BUILD is set to something
+if [ -z $REFERENCE_BUILD ]; then
+    REFERENCE_BUILD=0
+fi
+
+if [ $REFERENCE_BUILD -eq 1 ]; then
+    echo "Saving reference context"
+    build_avoidance_save_reference_context
+fi
 
 echo "All builds were successful"
 
diff --git a/build-tools/build-pkgs-serial b/build-tools/build-pkgs-serial
index a0061d59..103ef537 100755
--- a/build-tools/build-pkgs-serial
+++ b/build-tools/build-pkgs-serial
@@ -1,10 +1,22 @@
 #!/bin/bash
 
-# This program is a wrapper around build-srpms and build-rpms
+#
+# Copyright (c) 2018 Wind River Systems, Inc.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+#
+# Build first src.rpms, then rpms, from source, or from a downloaded tarball
+# or src.rpm plus our additional patches.
+#
+# This program is a wrapper around build-srpms-serial and build-rpms-serial
+#
 
 BUILD_PKGS_SERIAL_DIR="$(dirname "$(readlink -f "${BASH_SOURCE[0]}" )" )"
 
 source "${BUILD_PKGS_SERIAL_DIR}/git-utils.sh"
+source "${BUILD_PKGS_SERIAL_DIR}/build-avoidance-utils.sh"
 source "${BUILD_PKGS_SERIAL_DIR}/spec-utils"
 
 
@@ -13,14 +25,15 @@ usage () {
     echo "Usage: "
     echo "   Create source and Binary rpms:"
     echo "   Build optimizations (--no-descendants, --no-required, --no-build-info,"
-    echo "   --no-autoclean) are not recommended for the first build after a clone/pull,"
-    echo "   nor the final build prior to creating an iso or patch, but can be used"
-    echo "   for intermediate builds.  i.e. while debugging compilation failures." 
-    echo "      build-pkgs-serial [--no-descendants] [--no-required] [--no-build-info] [--no-autoclean] [--careful] [--formal] [ list of package names ]"
+    echo "   --no-autoclean, --no-build-avoidance) are not recommended for the first build"
+    echo "   after a clone/pull, nor the final build prior to creating an iso or patch,"
+    echo "   but can be used for intermediate builds."
+    echo "   i.e. while debugging compilation failures."
+    echo "      build-pkgs-serial [--build-avoidance | --no-build-avoidance] [--no-descendants] [--no-required] [--no-build-info] [--no-autoclean] [--careful] [--formal] [ list of package names ]"
     echo ""
     echo "   Delete source rpms, and the directories associated with it's creation:"
     echo "   Note: does not clean an edit environment"
-    echo "      build-pkgs-serial --clean [ list of package names ]"
+    echo "      build-pkgs-serial --clean [--build-avoidance | --no-build-avoidance] [ list of package names ]"
     echo ""
     echo "   Extract an src.rpm into a pair of git trees to aid in editing it's contents,"
     echo "   one for source code and one for metadata such as the spec file."
@@ -39,12 +52,17 @@ usage () {
 HELP=0
 CLEAN_FLAG=0
 EDIT_FLAG=0
+APPEND_LOG_FLAG=0
+BUILD_AVOIDANCE_FLAG=0
 STD_BUILD=1
 RT_BUILD=1
 INSTALLER_BUILD=0
 
+export BUILD_AVOIDANCE_URL=""
+
+
 # read the options
-TEMP=$(getopt -o h --long serial,rt,std,edit,no-meta-patch,no-descendants,no-required,no-build-info,no-autoclean,formal,careful,help,clean -n 'build-pkgs' -- "$@")
+TEMP=$(getopt -o h --long serial,rt,std,installer,edit,build-avoidance,no-build-avoidance,build-avoidance-dir:,build-avoidance-host:,build-avoidance-user:,build-avoidance-day:,no-meta-patch,no-descendants,no-required,no-build-info,no-autoclean,formal,careful,help,clean,append-log -n 'build-pkgs-serial' -- "$@")
 if [ $? -ne 0 ]; then
     usage
     exit 1
@@ -55,8 +73,21 @@ eval set -- "$TEMP"
 EXTRA_ARGS_COMMON=""
 EXTRA_ARGS_SRPM=""
 EXTRA_ARGS_RPM=""
+
+export BUILD_AVOIDANCE_OVERRIDE_DIR=""
+export BUILD_AVOIDANCE_OVERRIDE_HOST=""
+export BUILD_AVOIDANCE_OVERRIDE_USR=""
+export BUILD_AVOIDANCE_DAY=""
+
 while true ; do
     case "$1" in
+        --append-log)     APPEND_LOG_FLAG=1 ; shift ;;
+        --build-avoidance) BUILD_AVOIDANCE_FLAG=1 ; shift ;;
+        --no-build-avoidance) BUILD_AVOIDANCE_FLAG=0 ; shift ;;
+        --build-avoidance-dir)  BUILD_AVOIDANCE_OVERRIDE_DIR=$2; shift 2 ;;
+        --build-avoidance-host)  BUILD_AVOIDANCE_OVERRIDE_HOST=$2; shift 2 ;;
+        --build-avoidance-user)  BUILD_AVOIDANCE_OVERRIDE_USR=$2; shift 2 ;;
+        --build-avoidance-day) BUILD_AVOIDANCE_DAY=$2; shift 2 ;;
         --no-descendants) EXTRA_ARGS_COMMON+=" --no-descendants" ; shift ;;
         --formal)         EXTRA_ARGS_COMMON+=" --formal" ; shift ;;
         --careful)        EXTRA_ARGS_RPM+=" --careful" ; shift ;;
@@ -81,11 +112,59 @@ if [ $HELP -eq 1 ]; then
     exit 0
 fi
 
+function my_exit() {
+    build-rpms-parallel --std --tmpfs-clean
+    build-rpms-parallel --rt --tmpfs-clean
+}
+
+function my_sigint() {
+    echo "build-pkgs-parallel sigint"
+    pkill -SIGABRT -P $BASHPID &> /dev/null
+    echo "build-pkgs-parallel waiting"
+    wait
+    echo "build-pkgs-parallel wait complete"
+
+}
+
+function my_sighup() {
+    echo "build-pkgs-parallel sighup"
+    pkill -SIGABRT -P $BASHPID &> /dev/null
+    echo "build-pkgs-parallel waiting"
+    wait
+    echo "build-pkgs-parallel wait complete"
+}
+
+function my_sigabrt() {
+    echo "build-pkgs-parallel sigabrt"
+    pkill -SIGABRT -P $BASHPID &> /dev/null
+    echo "build-pkgs-parallel waiting"
+    wait
+    echo "build-pkgs-parallel wait complete"
+}
+
+function my_sigterm() {
+    echo "build-pkgs-parallel sigterm"
+    pkill -SIGABRT -P $BASHPID &> /dev/null
+    echo "build-pkgs-parallel waiting"
+    wait
+    echo "build-pkgs-parallel wait complete"
+}
+
+trap my_exit EXIT
+trap my_sigint INT
+trap my_sighup HUP
+trap my_sigabrt ABRT
+trap my_sigterm TERM
+
+# Note: For ease of parsing, a TARGETS list always begins and ends 
+# with a space.  An empty target list consistes of two spaces.
 TARGETS=" $@ "
-TARGETS_STD=" "
-TARGETS_RT=" "
-TARGETS_INSTALLER=" "
-TARGETS_MISC=" "
+EMPTY_TARGETS="  "
+
+TARGETS_STD="$EMPTY_TARGETS"
+TARGETS_RT="$EMPTY_TARGETS"
+TARGETS_INSTALLER="$EMPTY_TARGETS"
+TARGETS_MISC="$EMPTY_TARGETS"
 
 find_targets () {
    local centos_pkg_dirs=$1
@@ -155,14 +234,28 @@ find_targets () {
       fi
    done
 
-   echo "$RESULT"
+   if [ "$RESULT" == " " ]; then
+       echo "$EMPTY_LIST"
+   else
+       echo "$RESULT"
+   fi
    return 0
 }
 
+if [ $EDIT_FLAG -eq 1 ] || [ "$TARGETS" != "$EMPTY_TARGETS" ]; then
+   BUILD_AVOIDANCE_FLAG=0
+fi
+
+echo "BUILD_AVOIDANCE_FLAG=$BUILD_AVOIDANCE_FLAG"
 echo "CLEAN_FLAG=$CLEAN_FLAG"
 echo "EDIT_FLAG=$EDIT_FLAG"
 
-if [ "x$TARGETS" != "x  " ]; then
+if [ $BUILD_AVOIDANCE_FLAG -eq 1 ]; then
+    # Build Avoidance requested. Get URL of a usable context, if any.
+    export BUILD_AVOIDANCE_URL=$(get_build_avoidance_context)
+fi
+
+if [ "$TARGETS" != "$EMPTY_TARGETS" ]; then
    TARGETS_STD="$(find_targets centos_pkg_dirs)"
 
    BUILD_TYPE_SAVE="$BUILD_TYPE"
@@ -207,45 +300,51 @@ echo "TARGETS_INSTALLER='$TARGETS_INSTALLER'"
 echo "TARGETS_MISC='$TARGETS_MISC'"
 
 if [ $CLEAN_FLAG -eq 1 ]; then
+
+   if [ "$TARGETS" == "$EMPTY_TARGETS" ] && [ $BUILD_AVOIDANCE_FLAG -eq 1 ] ; then
+      build_avoidance_clean
+   fi
+
    if [ $STD_BUILD -eq 1 ]; then
-      if [ "x$TARGETS" == "x  " ] || [ "$TARGETS_STD" != " " ] || [ "$TARGETS_MISC" != " " ]; then
+      if [ "$TARGETS" == "$EMPTY_TARGETS" ] || [ "$TARGETS_STD" != "$EMPTY_TARGETS" ] || [ "$TARGETS_MISC" != "$EMPTY_TARGETS" ]; then
          if [ $EDIT_FLAG -ne 1 ]; then
             echo "${BUILD_PKGS_SERIAL_DIR}/build-rpms-serial --std --clean $EXTRA_ARGS_COMMON $EXTRA_ARGS_RPM $TARGETS_STD $TARGETS_MISC"
             ${BUILD_PKGS_SERIAL_DIR}/build-rpms-serial --std --clean $EXTRA_ARGS_COMMON $EXTRA_ARGS_RPM $TARGETS_STD $TARGETS_MISC || exit 1
 
          fi
       fi
-      if [ "x$TARGETS" == "x  " ] || [ "$TARGETS_STD" != " " ] || [ "$TARGETS_MISC" != " " ]; then
+      if [ "$TARGETS" == "$EMPTY_TARGETS" ] || [ "$TARGETS_STD" != "$EMPTY_TARGETS" ] || [ "$TARGETS_MISC" != "$EMPTY_TARGETS" ]; then
          echo "${BUILD_PKGS_SERIAL_DIR}/build-srpms-serial --std --clean $EXTRA_ARGS_COMMON $EXTRA_ARGS_SRPM $TARGETS_STD $TARGETS_MISC"
          ${BUILD_PKGS_SERIAL_DIR}/build-srpms-serial --std --clean $EXTRA_ARGS_COMMON $EXTRA_ARGS_SRPM $TARGETS_STD $TARGETS_MISC || exit 1
       fi
    fi
 
    if [ $RT_BUILD -eq 1 ]; then
-      if [ "x$TARGETS" == "x" ] || [ "$TARGETS_RT" != " " ] || [ "$TARGETS_MISC" != " " ]; then
+      if [ "$TARGETS" == "$EMPTY_TARGETS" ] || [ "$TARGETS_RT" != "$EMPTY_TARGETS" ] || [ "$TARGETS_MISC" != "$EMPTY_TARGETS" ]; then
          if [ $EDIT_FLAG -ne 1 ]; then
             echo "${BUILD_PKGS_SERIAL_DIR}/build-rpms-serial --rt --clean $EXTRA_ARGS_COMMON $EXTRA_ARGS_RPM $TARGETS_RT $TARGETS_MISC"
             ${BUILD_PKGS_SERIAL_DIR}/build-rpms-serial --rt --clean $EXTRA_ARGS_COMMON $EXTRA_ARGS_RPM $TARGETS_RT $TARGETS_MISC || exit 1
          fi
       fi
-      if [ "x$TARGETS" == "x  " ] || [ "$TARGETS_RT" != " " ] || [ "$TARGETS_MISC" != " " ]; then
+      if [ "$TARGETS" == "$EMPTY_TARGETS" ] || [ "$TARGETS_RT" != "$EMPTY_TARGETS" ] || [ "$TARGETS_MISC" != "$EMPTY_TARGETS" ]; then
          echo "${BUILD_PKGS_SERIAL_DIR}/build-srpms-serial --rt --clean $EXTRA_ARGS_COMMON $EXTRA_ARGS_SRPM $TARGETS_RT $TARGETS_MISC"
          ${BUILD_PKGS_SERIAL_DIR}/build-srpms-serial --rt --clean $EXTRA_ARGS_COMMON $EXTRA_ARGS_SRPM $TARGETS_RT $TARGETS_MISC || exit 1
       fi
    fi
 
    if [ $INSTALLER_BUILD -eq 1 ]; then
-      if [ "x$TARGETS" == "x" ] || [ "$TARGETS_INSTALLER" != " " ]; then
+      if [ "$TARGETS" == "$EMPTY_TARGETS" ] || [ "$TARGETS_INSTALLER" != "$EMPTY_TARGETS" ]; then
          if [ $EDIT_FLAG -ne 1 ]; then
             echo "${BUILD_PKGS_SERIAL_DIR}/build-rpms-serial --installer --clean $EXTRA_ARGS_COMMON $EXTRA_ARGS_RPM $TARGETS_INSTALLER"
             ${BUILD_PKGS_SERIAL_DIR}/build-rpms-serial --installer --clean $EXTRA_ARGS_COMMON $EXTRA_ARGS_RPM $TARGETS_INSTALLER || exit 1
          fi
       fi
-      if [ "x$TARGETS" == "x  " ] || [ "$TARGETS_INSTALLER" != " " ]; then
+      if [ "$TARGETS" == "$EMPTY_TARGETS" ] || [ "$TARGETS_INSTALLER" != "$EMPTY_TARGETS" ]; then
          echo "${BUILD_PKGS_SERIAL_DIR}/build-srpms-serial --installer --clean $EXTRA_ARGS_COMMON $EXTRA_ARGS_SRPM $TARGETS_INSTALLER"
          ${BUILD_PKGS_SERIAL_DIR}/build-srpms-serial --installer --clean $EXTRA_ARGS_COMMON $EXTRA_ARGS_SRPM $TARGETS_INSTALLER || exit 1
       fi
    fi
+
    exit $?
 fi
 
@@ -273,8 +372,18 @@ function launch_build()
    fi
 
    echo "Launching $build_type build, logging to $logfile"
+   if [ $APPEND_LOG_FLAG -eq 0 ] && [ -f $logfile ]; then
+       \rm $logfile
+   fi
 
    echo -e "\n######## $(date): Launching build-srpms-serial --$build_type $EXTRA_ARGS $@\n" | tee --append $logfile
+
+   echo "BUILD_AVOIDANCE_URL=$BUILD_AVOIDANCE_URL" | tee --append $logfile
+   if [ "x$BUILD_AVOIDANCE_URL" != "x" ]; then
+      echo "build_avoidance $build_type" | tee --append $logfile
+      build_avoidance $build_type 2>&1 | tee --append $logfile
+   fi
+
    # No clean flag, call build-srpms-serial followed by build-rpms-serial
    echo "${BUILD_PKGS_SERIAL_DIR}/build-srpms-serial --$build_type $EXTRA_ARGS_COMMON $EXTRA_ARGS_SRPM $targets" | tee --append $logfile
    ${BUILD_PKGS_SERIAL_DIR}/build-srpms-serial --$build_type $EXTRA_ARGS_COMMON $EXTRA_ARGS_SRPM $targets 2>&1 | tee --append $logfile
@@ -326,7 +435,7 @@ echo "Capture build context"
 git_context > "${MY_WORKSPACE}/CONTEXT"
 
 if [ $STD_BUILD -eq 1 ]; then
-   if [ "x$TARGETS" == "x  " ] || [ "$TARGETS_STD" != " " ] || [ "$TARGETS_MISC" != " " ]; then
+   if [ "$TARGETS" == "$EMPTY_TARGETS" ] || [ "$TARGETS_STD" != "$EMPTY_TARGETS" ] || [ "$TARGETS_MISC" != "$EMPTY_TARGETS" ]; then
       launch_build std
    else
       echo "Skipping 'std' build, no valid targets in list: $TARGETS"
@@ -336,7 +445,7 @@ else
 fi
 
 if [ $RT_BUILD -eq 1 ]; then
-   if [ "x$TARGETS" == "x  " ] || [ "$TARGETS_RT" != " " ] || [ "$TARGETS_MISC" != " " ]; then
+   if [ "$TARGETS" == "$EMPTY_TARGETS" ] || [ "$TARGETS_RT" != "$EMPTY_TARGETS" ] || [ "$TARGETS_MISC" != "$EMPTY_TARGETS" ]; then
       launch_build rt
    else
       echo "Skipping 'rt' build, no valid targets in list: $TARGETS"
@@ -346,7 +455,7 @@ else
 fi
 
 if [ $INSTALLER_BUILD -eq 1 ]; then
-   if [ "x$TARGETS" == "x  " ] || [ "$TARGETS_INSTALLER" != " " ] || [ "$TARGETS_MISC" != " " ]; then
+   if [ "$TARGETS" == "$EMPTY_TARGETS" ] || [ "$TARGETS_INSTALLER" != "$EMPTY_TARGETS" ] || [ "$TARGETS_MISC" != "$EMPTY_TARGETS" ]; then
       launch_build installer
    else
       echo "Skipping 'installer' build, no valid targets in list: $TARGETS"
@@ -355,6 +464,16 @@ else
    echo "Skipping 'installer' build"
 fi
 
+# Make sure REFERENCE_BUILD is set to something
+if [ -z $REFERENCE_BUILD ]; then
+    REFERENCE_BUILD=0
+fi
+
+if [ $REFERENCE_BUILD -eq 1 ]; then
+    echo "Saving reference context"
+    build_avoidance_save_reference_context
+fi
+
 echo "All builds were successful"
 
 exit 0
diff --git a/build-tools/build-rpms b/build-tools/build-rpms
index 937c406a..1867743e 100755
--- a/build-tools/build-rpms
+++ b/build-tools/build-rpms
@@ -1,6 +1,16 @@
 #!/bin/bash
 
+#
+# Copyright (c) 2018 Wind River Systems, Inc.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+#
+# Builds rpm files from src.rpm files.
+#
 # This program is a wrapper around build-rpms-parallel and build-rpms-serial
+#
 
 DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
 
diff --git a/build-tools/build-rpms-parallel b/build-tools/build-rpms-parallel
index 17234913..f56e9782 100755
--- a/build-tools/build-rpms-parallel
+++ b/build-tools/build-rpms-parallel
@@ -6,6 +6,24 @@
 # SPDX-License-Identifier: Apache-2.0
 #
 
+#
+# Builds rpm files from src.rpm files.
+#
+# This version compiles packages in parrallel if sufficient resources
+# (cpu's and memory) are available.
+#
+# The location of packages to be built is
+# $MY_WORKSPACE/<build-type>/rpmbuild/SRPMS.
+#
+# The build order is a derived from the BuildRequires in the 
+# spec files in the src.rpms.  Note that the BuildRequires sometimes
+# create dependency loops, so no correct order can be computed.  In these
+# cases we add a retry loop.  As long as one new package builds, we
+# keep retrying the loop, until all are built, or no progress is made.
+# So please don't panic and CTRL-C just because you see a few error
+# messages go by!
+#
+
 
 export ME=$(basename "$0")
 CMDLINE="$ME $@"
@@ -122,12 +140,10 @@ create-no-clean-list () {
    if [ ! -f $NO_CLEAN_LIST_FILE ]; then
        NEED_REBUILD=1
    else
-       if [ -f MY_BUILD_CFG ]; then
-           if [ -f MY_BUILD_CFG ]; then
-               find "$MY_BUILD_CFG" -not -newermm "$NO_CLEAN_LIST_FILE" | grep -q $(basename $MY_BUILD_CFG)
-               if [ $? -eq 0 ]; then
-                   NEED_REBUILD=1
-               fi
+       if [ -f $MY_BUILD_CFG ]; then
+           find "$MY_BUILD_CFG" -not -newermm "$NO_CLEAN_LIST_FILE" | grep -q $(basename $MY_BUILD_CFG)
+           if [ $? -eq 0 ]; then
+               NEED_REBUILD=1
            fi
        fi
    fi
diff --git a/build-tools/build-rpms-serial b/build-tools/build-rpms-serial
index 77cece6f..6358e586 100755
--- a/build-tools/build-rpms-serial
+++ b/build-tools/build-rpms-serial
@@ -6,6 +6,22 @@
 # SPDX-License-Identifier: Apache-2.0
 #
 
+# 
+# Builds rpm files from src.rpm files.
+#
+# This version compiles one package at a time.
+# 
+# The location of packages to be built is 
+# $MY_WORKSPACE/<build-type>/rpmbuild/SRPMS.
+#
+# The build order is a derived from the BuildRequires in the 
+# spec files in the src.rpms.  Note that the BuildRequires sometimes
+# create dependency loops, so no correct order can be computed.  In these
+# cases we add a retry loop.  As long as one new package builds, we
+# keep retrying the loop, until all are built, or no progress is made.
+# So please don't panic and CTRL-C just because you see a few error
+# messages go by!
+#
 
 export ME=$(basename "$0")
 CMDLINE="$ME $@"
@@ -63,12 +79,10 @@ create-no-clean-list () {
    if [ ! -f $NO_CLEAN_LIST_FILE ]; then
        NEED_REBUILD=1
    else
-       if [ -f MY_BUILD_CFG ]; then
-           if [ -f MY_BUILD_CFG ]; then
-               find "$MY_BUILD_CFG" -not -newermm "$NO_CLEAN_LIST_FILE" | grep -q $(basename $MY_BUILD_CFG)
-               if [ $? -eq 0 ]; then
-                   NEED_REBUILD=1
-               fi
+       if [ -f $MY_BUILD_CFG ]; then
+           find "$MY_BUILD_CFG" -not -newermm "$NO_CLEAN_LIST_FILE" | grep -q $(basename $MY_BUILD_CFG)
+           if [ $? -eq 0 ]; then
+               NEED_REBUILD=1
            fi
        fi
    fi
diff --git a/build-tools/build-srpms b/build-tools/build-srpms
index aef8a681..c0f1bafc 100755
--- a/build-tools/build-srpms
+++ b/build-tools/build-srpms
@@ -1,6 +1,24 @@
 #!/bin/bash
 
+#
+# Copyright (c) 2018 Wind River Systems, Inc.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+#
+# Create src.rpm files from source, or from a downloaded tarball
+# or src.rpm plus our additional patches.
+#
 # This program is a wrapper around build-srpms-parallel and build-srpms-serial
+#
+# The location of packages to be build are identified by
+# <distro>_pkg_dirs[_<opt-build-type>] files located at the root of
+# any git tree (e.g. istx/stx-integ/centos_pkg_dirs).
+#
+# The build of an individual package is driven by its build_srpm.data
+# file plus a <pkg-name>.spec file or an srpm_path file.
+#
 
 DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
 
diff --git a/build-tools/build-srpms-common.sh b/build-tools/build-srpms-common.sh
new file mode 100644
index 00000000..2afce635
--- /dev/null
+++ b/build-tools/build-srpms-common.sh
@@ -0,0 +1,187 @@
+#
+# Copyright (c) 2018 Wind River Systems, Inc.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+#
+# Functions common to build-srpm-serial and build-srpm-parallel.
+#
+
+SRC_BUILD_TYPE_SRPM="srpm"
+SRC_BUILD_TYPE_SPEC="spec"
+SRC_BUILD_TYPES="$SRC_BUILD_TYPE_SRPM $SRC_BUILD_TYPE_SPEC"
+
+
+str_lst_contains() {
+    TARGET="$1"
+    LST="$2"
+
+    if [[ $LST =~ (^|[[:space:]])$TARGET($|[[:space:]]) ]] ; then
+        return 0
+    else
+        return 1
+    fi
+}
+
+
+#
+# capture_md5sum_from_input_vars <src-build-type> <srpm-or-spec-path> <work-dir>
+#
+# Returns md5 data for all input files of a src.rpm.
+# Assumes PKG_BASE, ORIG_SRPM_PATH have been defined and the
+# build_srpm.data file has already been sourced.
+#
+# Arguments:
+#   src-build-type: Any single value from $SRC_BUILD_TYPES.
+#                   e.g. 'srpm' or 'spec'
+#   srpm-or-spec-path: Absolute path to an src.rpm, or to a
+#                      spec file.
+#   work-dir: Optional working directory.  If a path is
+#             specified but does not exist, it will be created.
+#
+# Returns: output of md5sum command with canonical path names
+#
+md5sums_from_input_vars () {
+    local SRC_BUILD_TYPE="$1"
+    local SRPM_OR_SPEC_PATH="$2"
+    local WORK_DIR="$3"
+
+    local TMP_FLAG=0
+    local LINK_FILTER='[/]stx[/]downloads[/]'
+
+    if ! str_lst_contains "$SRC_BUILD_TYPE" "$SRC_BUILD_TYPES" ; then
+        >&2  echo "ERROR: $FUNCNAME (${LINENO}): invalid arg: SRC_BUILD_TYPE='$SRC_BUILD_TYPE'"
+        return 1
+    fi
+
+    if [ -z $WORK_DIR ]; then
+        WORK_DIR=$(mktemp -d /tmp/${FUNCNAME}_XXXXXX)
+        if [ $? -ne 0 ]; then
+            >&2  echo "ERROR: $FUNCNAME (${LINENO}): mktemp -d /tmp/${FUNCNAME}_XXXXXX"
+            return 1
+        fi
+        TMP_FLAG=1
+    else
+        mkdir -p "$WORK_DIR"
+        if [ $? -ne 0 ]; then
+            >&2  echo "ERROR: $FUNCNAME (${LINENO}): mkdir -p '$WORK_DIR'"
+            return 1
+        fi
+    fi
+
+    local INPUT_FILES="$WORK_DIR/srpm_input.files"
+    local INPUT_LINKS="$WORK_DIR/srpm_input.links"
+    local INPUT_FILES_SORTED="$WORK_DIR/srpm_sorted_input.files"
+
+    if [ -f "$INPUT_LINKS" ]; then
+        \rm -f "$INPUT_LINKS"
+    fi
+
+    # Create lists of input files (INPUT_FILES) and symlinks (INPUT_LINKS).
+    # First elements are absolute paths...
+    find "$PKG_BASE" -type f > $INPUT_FILES
+    if [ $? -ne 0 ]; then
+        >&2  echo "ERROR: $FUNCNAME (${LINENO}): find '$PKG_BASE' -type f"
+        return 1
+    fi
+
+    if [ "$SRC_BUILD_TYPE" == "$SRC_BUILD_TYPE_SRPM" ]; then
+        find "$SRPM_OR_SPEC_PATH" -type f >> $INPUT_FILES
+        if [ $? -ne 0 ]; then
+            >&2  echo "ERROR: $FUNCNAME (${LINENO}): find '$SRPM_OR_SPEC_PATH' -type f"
+            return 1
+        fi
+    fi
+
+    # ...additional elements are based on values already sourced from
+    # build_srpm.data (COPY_LIST, SRC_DIR, COPY_LIST_TO_TAR, OPT_DEP_LIST)
+    # and may be relative to $PKG_BASE
+    #
+    # Use a subshell so any directory changes have no lastin effect.
+    (
+        cd $PKG_BASE
+        if [ "x$COPY_LIST" != "x" ]; then
+            ABS_COPY_LIST=$(readlink -f $COPY_LIST)
+            if [ $? -ne 0 ]; then
+                >&2  echo "ERROR: $FUNCNAME (${LINENO}): readlink -f '$COPY_LIST' -type f"
+                return 1
+            fi
+
+            find $ABS_COPY_LIST -type f >> $INPUT_FILES
+            if [ $? -ne 0 ]; then
+                >&2  echo "ERROR: $FUNCNAME (${LINENO}): find '$ABS_COPY_LIST' -type f"
+                return 1
+            fi
+
+            # Treat most links normally
+            find $ABS_COPY_LIST -type l | grep -v "$LINK_FILTER" >> $INPUT_FILES
+
+            # Links in the downloads directory likely point outside of $MY_REPO
+            # and might not be 'portable' from a build avoidance prespective.
+            # We'll treat these specially.
+            find $ABS_COPY_LIST -type l | grep "$LINK_FILTER" >> $INPUT_LINKS
+        fi
+
+        if [ "$SRC_BUILD_TYPE" == "$SRC_BUILD_TYPE_SPEC" ]; then
+            if [ "x$SRC_DIR" != "x" ]; then
+                if [ -d "$SRC_DIR" ]; then
+                    find $(readlink -f "$SRC_DIR") -type f | grep -v '[/][.]git$' | grep -v '[/][.]git[/]' >> $INPUT_FILES
+                    if [ $? -ne 0 ]; then
+                        >&2  echo "ERROR: $FUNCNAME (${LINENO}): find '$SRC_DIR' -type f"
+                        return 1
+                    fi
+                fi
+            fi
+
+            if [ "x$COPY_LIST_TO_TAR" != "x" ]; then
+                find $(readlink -f "$COPY_LIST_TO_TAR") -type f >> $INPUT_FILES
+                if [ $? -ne 0 ]; then
+                    >&2  echo "ERROR: $FUNCNAME (${LINENO}): find '$COPY_LIST_TO_TAR' -type f"
+                    return 1
+                fi
+            fi
+        fi
+
+        if [ "x$OPT_DEP_LIST" != "x" ]; then
+            find $(readlink -f "$OPT_DEP_LIST") -type f >> $INPUT_FILES 2> /dev/null
+            if [ $? -ne 0 ]; then
+                >&2  echo "ERROR: $FUNCNAME (${LINENO}): find '$OPT_DEP_LIST' -type f"
+                return 1
+            fi
+        fi
+    )
+    if [ $? -eq 1 ]; then
+        return -1
+    fi
+
+    # Create sorted, unique list of cononical paths
+    (
+        # Regular files, get canonical path
+        cat $INPUT_FILES | xargs readlink -f
+
+        # A Symlink that likely points outside of $MY_REPO.
+        # get canonical path to the symlink itself, and not
+        # to what the symlink points to.
+        if [ -f $INPUT_LINKS ]; then
+            while IFS= read -r f; do
+                echo "$(readlink -f $(dirname $f))/$(basename $f)"
+            done < "$INPUT_LINKS"
+        fi
+    ) | sort --unique > $INPUT_FILES_SORTED
+
+    # Remove $MY_REPO prefix from paths
+    cat $INPUT_FILES_SORTED | xargs md5sum | sed "s# $(readlink -f $MY_REPO)/# #"
+
+    if [ $TMP_FLAG -eq 0 ]; then
+        \rm -f $INPUT_FILES_SORTED
+        \rm -f $INPUT_FILES
+        if [ -f $INPUT_LINKS ]; then
+            \rm -f $INPUT_LINKS
+        fi
+    else
+        \rm -rf $WORK_DIR
+    fi
+
+    return 0
+}
diff --git a/build-tools/build-srpms-parallel b/build-tools/build-srpms-parallel
index 13fa4804..47e91e87 100755
--- a/build-tools/build-srpms-parallel
+++ b/build-tools/build-srpms-parallel
@@ -1,6 +1,26 @@
 #!/bin/bash
 # set -x
 
+#
+# Copyright (c) 2018 Wind River Systems, Inc.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+#
+# Create src.rpm files from source, or from a downloaded tarball
+# or src.rpm plus our additional patches.
+#
+# This version tries to compile many packages in parallel.
+#
+# The location of packages to be build are identified by
+# <distro>_pkg_dirs[_<opt-build-type>] files located at the root of
+# any git tree (e.g. stx/stx-integ/centos_pkg_dirs).
+#
+# The build of an individul package is driven by it's build_srpm.data
+# file plus a <pkg-name>.spec file or an srpm_path file.
+#
+
 export ME=$(basename "$0")
 CMDLINE="$ME $@"
 
@@ -9,6 +29,7 @@ source $BUILD_SRPMS_PARALLEL_DIR/git-utils.sh
 source $BUILD_SRPMS_PARALLEL_DIR/spec-utils
 source $BUILD_SRPMS_PARALLEL_DIR/srpm-utils
 source $BUILD_SRPMS_PARALLEL_DIR/classify
+source $BUILD_SRPMS_PARALLEL_DIR/build-srpms-common.sh
 
 
 INITIAL_DIR=$(pwd)
@@ -372,7 +393,7 @@ build_dir () {
          fi
 
          if [ "${ORIG_SRPM_PATH}x" == "x" ]; then
-            # handle mirror: definitions
+            # handle 3rd_party: definitions
             echo "$p" | grep "^3rd_party:" >/dev/null && ORIG_SRPM_PATH=$(echo $p | sed "s%^3rd_party:%$THIRD_PARTY_ROOT/%")
          fi
 
@@ -455,7 +476,7 @@ clean_srpm_dir () {
    local SRPM_OUT_NAME
    local INPUTS_TO_CLEAN=""
 
-   if [ $EXCLUDE_MD5 == "" ]; then
+   if [ "$EXCLUDE_MD5" == "" ]; then
        EXCLUDE_MD5=0
    fi
 
@@ -626,24 +647,15 @@ build_dir_srpm () {
       # Capture md5 data for all input files
       #
       local TARGET_SOURCES_DIR="$SOURCES_DIR/$TARGET_FOUND"
-      local INPUT_FILES="$TARGET_SOURCES_DIR/srpm_input.files"
-      local INPUT_FILES_SORTED="$TARGET_SOURCES_DIR/srpm_sorted_input.files"
       local INPUT_FILES_MD5="$TARGET_SOURCES_DIR/srpm_input.md5"
       local REFERENCE_MD5="$TARGET_SOURCES_DIR/srpm_reference.md5"
 
       mkdir -p "$TARGET_SOURCES_DIR"
-      find $PKG_BASE -type f > $INPUT_FILES
-      find $ORIG_SRPM_PATH -type f >> $INPUT_FILES
-         (
-         cd $PKG_BASE
-         if [ "x$COPY_LIST" != "x" ]; then
-            find $COPY_LIST -type f >> $INPUT_FILES
-         fi
-         )
-      cat $INPUT_FILES | xargs readlink -f | sort --unique > $INPUT_FILES_SORTED
-      \rm -f $INPUT_FILES
-      cat $INPUT_FILES_SORTED | xargs md5sum | sed "s# $(readlink -f $MY_REPO)/# #" > $INPUT_FILES_MD5
-      \rm -f $INPUT_FILES_SORTED
+      md5sums_from_input_vars "$SRC_BUILD_TYPE_SRPM" "$ORIG_SRPM_PATH" "$TARGET_SOURCES_DIR" > "$INPUT_FILES_MD5"
+      if [ $? -ne 0 ]; then
+         echo "ERROR: $FUNCNAME (${LINENO}): md5sums_from_input_vars '$SRC_BUILD_TYPE_SRPM' '$ORIG_SRPM_PATH' '$TARGET_SOURCES_DIR'"
+         return 1
+      fi
       echo "Wrote: $INPUT_FILES_MD5"
 
       #
@@ -946,38 +958,15 @@ build_dir_spec () {
          # Capture md5 data for all input files
          #
          local TARGET_SOURCES_DIR="$SOURCES_DIR/$TARGET_FOUND"
-         local INPUT_FILES="$TARGET_SOURCES_DIR/srpm_input.files"
-         local INPUT_FILES_SORTED="$TARGET_SOURCES_DIR/srpm_sorted_input.files"
          local INPUT_FILES_MD5="$TARGET_SOURCES_DIR/srpm_input.md5"
          local REFERENCE_MD5="$TARGET_SOURCES_DIR/srpm_reference.md5"
 
          mkdir -p "$TARGET_SOURCES_DIR"
-         find $PKG_BASE -type f > $INPUT_FILES
-         find $ORIG_SRPM_PATH -type f >> $INPUT_FILES
-            (
-            cd $PKG_BASE
-            if [ "x$SRC_DIR" != "x" ]; then
-               if [ -d "$SRC_DIR" ]; then
-                  find $SRC_DIR -type f | grep -v '[/][.]git$' | grep -v '[/][.]git[/]' >> $INPUT_FILES
-               fi
-            fi
-
-            if [ "x$COPY_LIST" != "x" ]; then
-               find $COPY_LIST -type f >> $INPUT_FILES
-            fi
-
-            if [ "x$COPY_LIST_TO_TAR" != "x" ]; then
-               find $COPY_LIST_TO_TAR -type f >> $INPUT_FILES
-            fi
-
-            if [ "x$OPT_DEP_LIST" != "x" ]; then
-               find $OPT_DEP_LIST -type f >> $INPUT_FILES 2> /dev/null
-            fi
-            )
-         cat $INPUT_FILES | xargs readlink -f | sort --unique > $INPUT_FILES_SORTED
-         \rm -f $INPUT_FILES
-         cat $INPUT_FILES_SORTED | xargs md5sum | sed "s# $(readlink -f $MY_REPO)/# #" > $INPUT_FILES_MD5
-         \rm -f $INPUT_FILES_SORTED
+         md5sums_from_input_vars "$SRC_BUILD_TYPE_SPEC" "$SPEC" "$TARGET_SOURCES_DIR" > "$INPUT_FILES_MD5"
+         if [ $? -ne 0 ]; then
+             echo "ERROR: $FUNCNAME (${LINENO}): md5sums_from_input_vars '$SRC_BUILD_TYPE_SPEC' '$SPEC' '$TARGET_SOURCES_DIR'"
+             return 1
+         fi
          echo "Wrote: $INPUT_FILES_MD5"
 
          #
diff --git a/build-tools/build-srpms-serial b/build-tools/build-srpms-serial
index 4398115b..fbdd33cb 100755
--- a/build-tools/build-srpms-serial
+++ b/build-tools/build-srpms-serial
@@ -1,6 +1,26 @@
 #!/bin/bash
 # set -x
 
+#
+# Copyright (c) 2018 Wind River Systems, Inc.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
+#
+# Create src.rpm files from source, or from a downloaded tarball
+# or src.rpm plus our additional patches.
+#
+# This version only tries to compile on package at a time.
+#
+# The location of packages to be build are identified by
+# <distro>_pkg_dirs[_<opt-build-type>] files located at the root of
+# any git tree (e.g. stx/stx-integ/centos_pkg_dirs).
+#
+# The build of an individul package is driven by it's build_srpm.data
+# file plus a <pkg-name>.spec file or an srpm_path file.
+#
+
 export ME=$(basename "$0")
 CMDLINE="$ME $@"
 
@@ -10,6 +30,7 @@ source $BUILD_SRPMS_SERIAL_DIR/git-utils.sh
 source $BUILD_SRPMS_SERIAL_DIR/spec-utils
 source $BUILD_SRPMS_SERIAL_DIR/srpm-utils
 source $BUILD_SRPMS_SERIAL_DIR/classify
+source $BUILD_SRPMS_PARALLEL_DIR/build-srpms-common.sh
 
 
 INITIAL_DIR=$(pwd)
@@ -438,7 +459,7 @@ clean_srpm_dir () {
    local SRPM_OUT_NAME
    local INPUTS_TO_CLEAN=""
 
-   if [ $EXCLUDE_MD5 == "" ]; then
+   if [ "$EXCLUDE_MD5" == "" ]; then
        EXCLUDE_MD5=0
    fi
 
@@ -603,24 +624,15 @@ build_dir_srpm () {
       # Capture md5 data for all input files
       #
       local TARGET_SOURCES_DIR="$SOURCES_DIR/$TARGET_FOUND"
-      local INPUT_FILES="$TARGET_SOURCES_DIR/srpm_input.files"
-      local INPUT_FILES_SORTED="$TARGET_SOURCES_DIR/srpm_sorted_input.files"
       local INPUT_FILES_MD5="$TARGET_SOURCES_DIR/srpm_input.md5"
       local REFERENCE_MD5="$TARGET_SOURCES_DIR/srpm_reference.md5"
 
       mkdir -p "$TARGET_SOURCES_DIR"
-      find $PKG_BASE -type f > $INPUT_FILES
-      find $ORIG_SRPM_PATH -type f >> $INPUT_FILES
-         (
-         cd $PKG_BASE
-         if [ "x$COPY_LIST" != "x" ]; then
-            find $COPY_LIST -type f >> $INPUT_FILES
-         fi
-         )
-      cat $INPUT_FILES | xargs readlink -f | sort --unique > $INPUT_FILES_SORTED
-      \rm -f $INPUT_FILES
-      cat $INPUT_FILES_SORTED | xargs md5sum | sed "s# $(readlink -f $MY_REPO)/# #" > $INPUT_FILES_MD5
-      \rm -f $INPUT_FILES_SORTED
+      md5sums_from_input_vars "$SRC_BUILD_TYPE_SRPM" "$ORIG_SRPM_PATH" "$TARGET_SOURCES_DIR" > "$INPUT_FILES_MD5"
+      if [ $? -ne 0 ]; then
+         echo "ERROR: $FUNCNAME (${LINENO}): md5sums_from_input_vars '$SRC_BUILD_TYPE_SRPM' '$ORIG_SRPM_PATH' '$TARGET_SOURCES_DIR'"
+         return 1
+      fi
       echo "Wrote: $INPUT_FILES_MD5"
 
       #
@@ -922,38 +934,15 @@ build_dir_spec () {
          # Capture md5 data for all input files
          #
          local TARGET_SOURCES_DIR="$SOURCES_DIR/$TARGET_FOUND"
-         local INPUT_FILES="$TARGET_SOURCES_DIR/srpm_input.files"
-         local INPUT_FILES_SORTED="$TARGET_SOURCES_DIR/srpm_sorted_input.files"
          local INPUT_FILES_MD5="$TARGET_SOURCES_DIR/srpm_input.md5"
          local REFERENCE_MD5="$TARGET_SOURCES_DIR/srpm_reference.md5"
 
          mkdir -p "$TARGET_SOURCES_DIR"
-         find $PKG_BASE -type f > $INPUT_FILES
-         find $ORIG_SRPM_PATH -type f >> $INPUT_FILES
-            (
-            cd $PKG_BASE
-            if [ "x$SRC_DIR" != "x" ]; then
-               if [ -d "$SRC_DIR" ]; then
-                  find $SRC_DIR -type f | grep -v '[/][.]git$' | grep -v '[/][.]git[/]' >> $INPUT_FILES
-               fi
-            fi
-
-            if [ "x$COPY_LIST" != "x" ]; then
-               find $COPY_LIST -type f >> $INPUT_FILES
-            fi
-
-            if [ "x$COPY_LIST_TO_TAR" != "x" ]; then
-               find $COPY_LIST_TO_TAR -type f >> $INPUT_FILES
-            fi
-
-            if [ "x$OPT_DEP_LIST" != "x" ]; then
-               find $OPT_DEP_LIST -type f >> $INPUT_FILES 2> /dev/null
-            fi
-            )
-         cat $INPUT_FILES | xargs readlink -f | sort --unique > $INPUT_FILES_SORTED
-         \rm -f $INPUT_FILES
-         cat $INPUT_FILES_SORTED | xargs md5sum | sed "s# $(readlink -f $MY_REPO)/# #" > $INPUT_FILES_MD5
-         \rm -f $INPUT_FILES_SORTED
+         md5sums_from_input_vars "$SRC_BUILD_TYPE_SPEC" "$SPEC" "$TARGET_SOURCES_DIR" > "$INPUT_FILES_MD5"
+         if [ $? -ne 0 ]; then
+             echo "ERROR: $FUNCNAME (${LINENO}): md5sums_from_input_vars '$SRC_BUILD_TYPE_SPEC' '$SPEC' '$TARGET_SOURCES_DIR'"
+             return 1
+         fi
          echo "Wrote: $INPUT_FILES_MD5"
 
          #
diff --git a/build-tools/git-utils.sh b/build-tools/git-utils.sh
index 94490df1..de432464 100755
--- a/build-tools/git-utils.sh
+++ b/build-tools/git-utils.sh
@@ -9,6 +9,10 @@
 # by repo manifests.
 #
 
+git_ctx_root_dir () {
+    dirname "${MY_REPO}"
+}
+
 #
 # git_list <dir>:
 #      Return a list of git root directories found under <dir>
@@ -22,12 +26,12 @@ git_list () {
 
 # GIT_LIST: A list of root directories for all the gits under $MY_REPO/..
 #           as absolute paths.
-export GIT_LIST=$(git_list "$(dirname "${MY_REPO}")")
+export GIT_LIST=$(git_list "$(git_ctx_root_dir)")
 
 
 # GIT_LIST_REL: A list of root directories for all the gits under $MY_REPO/..
 #               as relative paths.
-export GIT_LIST_REL=$(for p in $GIT_LIST; do echo .${p#$(dirname ${MY_REPO})}; done)
+export GIT_LIST_REL=$(for p in $GIT_LIST; do echo .${p#$(git_ctx_root_dir)}; done)
 
 
 #
@@ -85,7 +89,9 @@ git_list_containing_tag () {
 
 git_context () {
     (
-    cd $MY_REPO
+    cd $(git_ctx_root_dir)
+
+    local d
     for d in $GIT_LIST_REL; do
         (
         cd ${d}
@@ -95,3 +101,48 @@ git_context () {
     done
     )
 }
+
+#
+# git_test_context <context>:
+#
+# Test if all commits referenced in the context are present
+# in the history of the gits in their current checkout state.
+#
+# Returns: 0 = context is present in git history
+#          1 = At least one element of context is not present
+#          2 = error
+#
+git_test_context () {
+    local context="$1"
+    local query=""
+    local target_hits=0
+    local actual_hits=0
+
+    if [ ! -f "$context" ]; then
+        return 2
+    fi
+
+    query=$(mktemp "/tmp/git_test_context_XXXXXX")
+    if [ "$query" == "" ]; then
+        return 2
+    fi
+
+    # Transform a checkout context into a query that prints
+    # all the commits that are found in the git history.
+    #
+    # Limit search to last 500 commits in the interest of speed.
+    # I don't expect to be using contexts more than a few weeks old.
+    cat "$context" | \
+        sed "s#checkout -f \([a-e0-9]*\)#rev-list --max-count=500 HEAD | \
+        grep \1#" > $query
+
+    target_hits=$(cat "$context" | wc -l)
+    actual_hits=$(cd $(git_ctx_root_dir); source $query | wc -l)
+    \rm $query
+
+    if [ $actual_hits -eq $target_hits ]; then
+        return 0
+    fi
+
+    return 1
+}
diff --git a/build-tools/sign-secure-boot b/build-tools/sign-secure-boot
index 4401e5cf..19a6c62f 100755
--- a/build-tools/sign-secure-boot
+++ b/build-tools/sign-secure-boot
@@ -1,5 +1,11 @@
 #!/bin/bash
 
+#
+# Copyright (c) 2018 Wind River Systems, Inc.
+#
+# SPDX-License-Identifier: Apache-2.0
+#
+
 # This script calls into an external signing server to perform signing of some
 # packages in the system.  The old packages (which are typically generated by
 # the build system and signed by placeholder keys) are overwritten by the new
@@ -264,7 +270,7 @@ function rebuild_pkgs
 	fi
 
         echo "Performing rebuild of packages: $PKGS_TO_REBUILD"
-        FORMAL_BUILD=0 build-pkgs --no-descendants --no-build-info --no-required --careful $PKGS_TO_REBUILD > $LOGFILE 2>&1
+        FORMAL_BUILD=0 build-pkgs --no-descendants --no-build-info --no-required --careful --append-log $PKGS_TO_REBUILD > $LOGFILE 2>&1
 
 	if [ $? -ne 0 ]; then
 		echo "Could not rebuild packages: $PKGS_TO_REBUILD -- see $LOGFILE for details"