@@ -53,10 +53,16 @@ jobs:

       # Backports or PR that target a release branch directly should mention the target branch in the title, for example:

       # [X.Y backport] Some change that needs backporting to X.Y

       # [X.Y] Change directly targeting the X.Y branch

-      - name: Get branch from PR title

+      - name: Check release branch

         id: title_branch

-        run: echo "$PR_TITLE" | sed -n 's/^\[\([0-9]*\.[0-9]*\)[^]]*\].*/branch=\1/p' >> $GITHUB_OUTPUT

+        run: |

+          # get the intended major version prefix ("[27.1 backport]" -> "27.") from the PR title.

+          [[ "$PR_TITLE" =~ ^\[\([0-9]*\.\)[^]]*\] ]] && branch="${BASH_REMATCH[1]}"

-      - name: Check release branch

-        if: github.event.pull_request.base.ref != steps.title_branch.outputs.branch && !(github.event.pull_request.base.ref == 'master' && steps.title_branch.outputs.branch == '')

-        run: echo "::error::PR title suggests targetting the ${{ steps.title_branch.outputs.branch }} branch, but is opened against ${{ github.event.pull_request.base.ref }}" && exit 1

+          # get major version prefix from the release branch ("27.x -> "27.")

+          [[ "$GITHUB_BASE_REF" =~ ^\([0-9]*\.\) ]] && target_branch="${BASH_REMATCH[1]}"

+

+          if [[ "$GITHUB_BASE_REF" != "$branch" ]] && ! [[ "$GITHUB_BASE_REF" == "master" && "$branch" == "" ]]; then

+              echo "::error::PR is opened against the $GITHUB_BASE_REF branch, but its title suggests otherwise."

+              exit 1

+          fi