fix: add a delay before the contributors workflow sets auto-merge

Problem: when auto-merge is set, the PR merges as soon as the required check
status is okay, meaning that the next job that uploads test coverage
always fails (branch is deleted). This is not blocking but kind of untidy.

Solution: introduced a loop that waits for all PR jobs to complete
before auto-merge is enabled.

Signed-off-by: Frederic BIDON <fredbi@yahoo.com>

Author: fredbi

.github/workflows/contributors.yml

@@ -81,6 +81,36 @@ jobs:
         name: Auto-approve PR
         run: gh pr review --approve "$PR_URL"
       -
-        # TODO: should wait for all workflows to complete before merging
+        name: Wait for all workflow runs to complete
+        run: |
+          PR_NUMBER=$(echo "$PR_URL" | grep -oP '\d+$')
+          echo "Waiting for all checks to complete on PR #${PR_NUMBER}..."
+
+          MAX_WAIT=600  # 10 minutes max wait
+          ELAPSED=0
+          SLEEP_INTERVAL=10
+
+          while [ $ELAPSED -lt $MAX_WAIT ]; do
+            # Get all workflow runs for this PR's head SHA
+            PR_DATA=$(gh pr view "$PR_NUMBER" --json headRefOid,statusCheckRollup)
+            HEAD_SHA=$(echo "$PR_DATA" | jq -r '.headRefOid')
+
+            # Check if any workflows are still in progress
+            IN_PROGRESS=$(echo "$PR_DATA" | jq -r '.statusCheckRollup[] | select(.status == "IN_PROGRESS" or .status == "QUEUED" or .status == "PENDING") | .name' | wc -l)
+
+            if [ "$IN_PROGRESS" -eq 0 ]; then
+              echo "::notice::All workflow runs completed for SHA ${HEAD_SHA}"
+              break
+            fi
+
+            echo "Still waiting for $IN_PROGRESS check(s) to complete..."
+            sleep $SLEEP_INTERVAL
+            ELAPSED=$((ELAPSED + SLEEP_INTERVAL))
+          done
+
+          if [ $ELAPSED -ge $MAX_WAIT ]; then
+            echo "::warning::Timeout waiting for all checks to complete, proceeding anyway"
+          fi
+      -
         name: Auto-merge PR
         run: gh pr merge --auto --rebase "$PR_URL"