Unify usages of checking for existing changes (1/2)

Create new function setup_commit_message in common.sh that sets the
commit message after checking for its existance. This check is
currently done in four places, the code has been copied around for this.
Let's unify this so that we only have a single piece of this code block.

For this change, use  the new function only for translation update.
The next change will update all other places. We're doing this in steps
in case of problems.

Change-Id: I80c7f81b0b7f225fbf1e1564239f40b5df8537d9

jenkins/scripts/common.sh

@@ -20,3 +20,40 @@ function setup_git {
     # from. Otherwise git review will complain.
     git checkout -B proposals
 }
+
+# See if there is already open change. If so, get the change id for
+# the existing change for use in the commit msg.
+# Sets variable CHANGE_ID if there is a previous change.
+# Sets variable COMMIT_MSG to include change id and INITIAL_COMMIT_MSG.
+function setup_commit_message {
+    local PROJECT=$1
+    local USERNAME=$2
+    local BRANCH=$3
+    local TOPIC=$4
+    local INITIAL_COMMIT_MSG=$5
+
+    # See if there is an open change, if so, get the change id for the
+    # existing change for use in the commit message.
+    local change_info=$(ssh -p 29418 $USERNAME@review.openstack.org \
+        gerrit query --current-patch-set status:open project:$PROJECT \
+        owner:$USERNAME branch:$BRANCH topic:$TOPIC)
+    local previous=$(echo "$change_info" | grep "^  number:" | awk '{print $2}')
+    if [ -n "$previous" ]; then
+        CHANGE_ID=$(echo "$change_info" | grep "^change" | awk '{print $2}')
+        # read returns a non zero value when it reaches EOF. Because we use a
+        # heredoc here it will always reach EOF and return a nonzero value.
+        # Disable -e temporarily to get around the read.
+        # The reason we use read is to allow for multiline variable content
+        # and variable interpolation. Simply double quoting a string across
+        # multiple lines removes the newlines.
+        set +e
+        read -d '' COMMIT_MSG <<EOF
+$INITIAL_COMMIT_MSG
+
+Change-Id: $change_id
+EOF
+        set -e
+    else
+        COMMIT_MSG=$INITIAL_COMMIT_MSG
+    fi
+}

jenkins/scripts/common_translation_update.sh

@@ -16,6 +16,9 @@
 
 source /usr/local/jenkins/slave_scripts/common.sh
 
+# Topic to use for our changes
+TOPIC=zanata/translations
+
 # Used for setup.py babel commands
 QUIET="--quiet"
 
@@ -142,7 +145,7 @@ function setup_review {
     local branch=${1:-master}
     FULL_PROJECT=$(grep project .gitreview  | cut -f2 -d= |sed -e 's/\.git$//')
     set +e
-    read -d '' COMMIT_MSG <<EOF
+    read -d '' INITIAL_COMMIT_MSG <<EOF
 Imported Translations from Zanata
 
 For more information about this automatic import see:
@@ -154,21 +157,8 @@ EOF
     # See if there is an open change in the zanata/translations
     # topic. If so, get the change id for the existing change for use
     # in the commit msg.
-    change_info=$(ssh -p 29418 proposal-bot@review.openstack.org gerrit query --current-patch-set status:open project:$FULL_PROJECT branch:$branch topic:zanata/translations owner:proposal-bot)
-    previous=$(echo "$change_info" | grep "^  number:" | awk '{print $2}')
-    if [ -n "$previous" ]; then
-        change_id=$(echo "$change_info" | grep "^change" | awk '{print $2}')
-        # Read returns a non zero value when it reaches EOF. Because we use a
-        # heredoc here it will always reach EOF and return a nonzero value.
-        # Disable -e temporarily to get around the read.
-        set +e
-        read -d '' COMMIT_MSG <<EOF
-$COMMIT_MSG
+    setup_commit_message $FULL_PROJECT proposal-bot $branch $TOPIC "$INITIAL_COMMIT_MSG"
 
-Change-Id: $change_id
-EOF
-        set -e
-    fi
     # If the open change an already approved, let's not queue a new
     # patch but let's merge the other patch first.
     # This solves the problem that when the gate pipeline backup
@@ -176,9 +166,9 @@ EOF
     # update it will always get sniped out of the gate by another.
     # It also helps, when you approve close to the time this job is
     # run.
-    if [ -n "$previous" ]; then
+    if [ -n "$CHANGE_ID" ]; then
         # Use the JSON format since it is very compact and easy to grep
-        change_info=$(ssh -p 29418 proposal-bot@review.openstack.org gerrit query --current-patch-set --format=JSON $change_id)
+        change_info=$(ssh -p 29418 proposal-bot@review.openstack.org gerrit query --current-patch-set --format=JSON $CHANGE_ID)
         # Check for:
         # 1) Workflow approval (+1)
         # 2) no -1/-2 by Jenkins
@@ -215,7 +205,7 @@ EOF
         set +e
         # We cannot rely on the default branch in .gitreview being
         # correct so we are very explicit here.
-        output=$(git review -t zanata/translations $branch)
+        output=$(git review -t $TOPIC $branch)
         ret=$?
         [[ "$ret" -eq "0" || "$output" =~ "No changes between prior commit" ]]
         success=$?