Revert "Revert "update repo sync"" (#17935)

Author: rachmari

.github/allowed-actions.js

@@ -33,7 +33,7 @@ module.exports = [
   "rachmari/actions-add-new-issue-to-column@1a459ef92308ba7c9c9dc2fcdd72f232495574a9",
   "rachmari/labeler@832d42ec5523f3c6d46e8168de71cd54363e3e2e",
   "repo-sync/github-sync@3832fe8e2be32372e1b3970bbae8e7079edeec88",
-  "repo-sync/pull-request@33777245b1aace1a58c87a29c90321aa7a74bd7d",
+  "repo-sync/pull-request@65194d8015be7624d231796ddee1cd52a5023cb3", // repo-sync/pull-request@v2.6
   "someimportantcompany/github-actions-slack-message@0b470c14b39da4260ed9e3f9a4f1298a74ccdefd",
   "tjenkinson/gh-action-auto-merge-dependency-updates@4d7756c04d9d999c5968697a621b81c47f533d61",
   "EndBug/add-and-commit@9358097a71ad9fb9e2f9624c6098c89193d83575",

.github/workflows/repo-sync.yml

@@ -32,7 +32,7 @@ jobs:
 
       - name: Create pull request
         id: create-pull
-        uses: repo-sync/pull-request@33777245b1aace1a58c87a29c90321aa7a74bd7d
+        uses: repo-sync/pull-request@65194d8015be7624d231796ddee1cd52a5023cb3
         env:
           GITHUB_TOKEN: ${{ secrets.OCTOMERGER_PAT_WITH_REPO_AND_WORKFLOW_SCOPE }}
         with:
@@ -52,6 +52,22 @@ jobs:
           base: main
           author: Octomerger
 
+      # Sometimes the `repo-sync` branch gets created but GitHub thinks a pull
+      # request is already attached to the branch. This may happen when an
+      # external contributor creates a pull request for the `repo-sync` branch
+      # in a fork, then deletes their repository. If there were changes added
+      # to the `repo-sync` branch but no pull request can be found, we should
+      # fail. The failure will then be sent to Slack in the last step.
+      - name: Check for pull request creation errors
+        if: ${{ !steps.find-pull-request.outputs.number }}
+        id: check-pr-creation
+        run: |
+          LINES_CHANGED=$(git diff --name-only "main" "repo-sync" -- | wc -l | awk '{print $1}')
+          if [[ "$LINES_CHANGED" != "0" ]]; then
+            echo 'Unable to create a new PR for the existing branch `repo-sync`. Delete that branch and re-run this workflow to generate a new PR.'
+            exit 1 # prevents further steps from running
+          fi
+
       - name: Approve pull request
         if: ${{ steps.find-pull-request.outputs.number }}
         uses: juliangruber/approve-pull-request-action@c530832d4d346c597332e20e03605aa94fa150a8