Re-run PR checks after appending Change Log fragment

.changelog/777.internal.md

@@ -0,0 +1 @@
+Re-run PR checks after appending Change Log fragment

.github/workflows/ci-renovate.yml

@@ -27,21 +27,36 @@ jobs:
           fetch-depth: 0
           # Checkout pull request HEAD commit instead of merge commit.
           ref: ${{ github.event.pull_request.head.sha }}
+          # Needed to enable checks re-run.
+          token: ${{ secrets.PAT }}
       - name: Set workflow variables
         # Id is needed to access output in a next step.
         id: vars
         run: |
           echo "FILE_NAME=.changelog/${{ github.event.pull_request.number }}.internal.md" >> $GITHUB_OUTPUT
+      - name: Check if Change Log file exists
+        id: check_file
+        run: |
+          if [[ ! -f "${{ steps.vars.outputs.FILE_NAME }}" ]]; then
+            # Change Log file does not exist, continue with other steps.
+            echo "FILE_EXISTS=false" >> $GITHUB_OUTPUT
+          else
+            # File exists, skip all other steps.
+            echo "FILE_EXISTS=true" >> $GITHUB_OUTPUT
+          fi
       - name: Create Change Log file
+        if: steps.check_file.outputs.FILE_EXISTS == 'false'
         run: |
           echo "${{ github.event.pull_request.title }}" > ${{ steps.vars.outputs.FILE_NAME }}
       - name: Commit Change Log file
+        if: steps.check_file.outputs.FILE_EXISTS == 'false'
         run: |
           # Set git user email and name to match author of the last commit.
           git config --local user.email "$(git log --pretty='%ae' -1)"
           git config --local user.name "$(git log --pretty=format:'%an' -1)"
           git add ${{ steps.vars.outputs.FILE_NAME }}
           git commit --amend --no-edit
       - name: Push changes back to branch
+        if: steps.check_file.outputs.FILE_EXISTS == 'false'
         run: |
           git push --force-with-lease origin HEAD:refs/heads/${{ github.head_ref }}