GH-704 - Add script to back-port commits.

The script creates tickets for the back-ports, cherry-picks the latest commit of the current branch and adapts the commit messages of them to the ticket ids of the newly created tickets.

etc/create-backport-tickets.sh

@@ -0,0 +1,40 @@
+#!/bin/bash
+# Format $ticketNumer $targetVersion[]
+
+sourceGh="GH-$1"
+branch=$(git branch --show-current)
+json=$(gh issue view $1 --json=title,labels)
+
+title=$(echo $json | jq -r '.title')
+labels=$(echo $json | jq -r '.labels[].name' | paste -sd ',' -)
+
+number=$1
+
+# For each of the target versions
+for version in ${@:2}
+do
+	number=$(gh issue create --title "$title" --body "Back-port of $sourceGh." --label "$labels" --assignee "@me" --milestone "$version" | awk -F '/' '{print $NF}')
+
+	# Turn 1.5.6 into 1.5.x
+	targetBranch="$(echo "$version" | grep -oE '^[0-9]+\.[0-9]+').x"
+
+	# Checkout target branch and cherry-pick commit
+
+	echo "Checking out branch $targetBranch"
+	git checkout $targetBranch
+
+	echo "Cherry-pick commit from $branch"
+	git cherry-pick $branch
+
+	# Replace ticket reference with new one
+	targetGh="GH-$number"
+	expression="s/$sourceGh/$targetGh/g"
+	message=$(git log -1 --pretty=format:"%s" | sed $expression)
+
+	# Update commit message to refer to new ticket
+	echo "Adapt commit message from $sourceGh to $targetGh"
+	git commit --amend -m "$message"
+done
+
+# Return to original branch
+git checkout $branch