fix(ci): distinguish stale wait outcomes in dependabot automerge

Agent-Logs-Url: https://github.com/wallstop/fortress-rollback/sessions/c3354c08-7ed6-4593-9d54-9d1ba779b96d

Co-authored-by: wallstop <1045249+wallstop@users.noreply.github.com>

Author: Copilot

scripts/ci/enable-dependabot-automerge.sh

@@ -67,14 +67,14 @@ wait_for_required_checks() {
     while ((elapsed <= REQUIRED_CHECKS_APPEAR_TIMEOUT_SECONDS)); do
         if is_stale_event; then
             echo "PR head moved while waiting for required checks; skipping stale auto-merge attempt."
-            return 0
+            return 2
         fi
 
         required_count="$(required_checks_count)"
         if [[ "$required_count" =~ ^[0-9]+$ ]] && ((required_count > 0)); then
             if is_stale_event; then
                 echo "PR head moved after required checks appeared; skipping stale auto-merge attempt."
-                return 0
+                return 2
             fi
             echo "Waiting for $required_count required checks to pass before enabling auto-merge."
             if ! gh pr checks "$PR_URL" --required --watch --fail-fast --interval "$REQUIRED_CHECKS_WATCH_INTERVAL_SECONDS"; then
@@ -136,7 +136,15 @@ if [[ "$allow_rebase_merge" == "true" || "$allow_merge_commit" == "true" ]]; the
     exit 1
 fi
 
-if ! wait_for_required_checks; then
+if wait_for_required_checks; then
+    wait_status=0
+else
+    wait_status=$?
+fi
+if [[ "$wait_status" -eq 2 ]]; then
+    exit 0
+fi
+if [[ "$wait_status" -ne 0 ]]; then
     exit 1
 fi
 

scripts/tests/test_enable_dependabot_automerge.py

@@ -282,6 +282,7 @@ def test_skips_when_head_becomes_stale_while_waiting(tmp_path: Path) -> None:
     )
     assert result.returncode == 0
     assert "PR head moved while waiting for required checks" in result.stdout
+    assert "after required checks completed" not in result.stdout
 
     log_lines = (tmp_path / "gh.log").read_text(encoding="utf-8").splitlines()
     assert len(log_lines) == 1
@@ -303,6 +304,7 @@ def test_skips_when_head_becomes_stale_after_checks_appear(tmp_path: Path) -> No
     )
     assert result.returncode == 0
     assert "PR head moved after required checks appeared" in result.stdout
+    assert "after required checks completed" not in result.stdout
 
     log_lines = (tmp_path / "gh.log").read_text(encoding="utf-8").splitlines()
     assert len(log_lines) == 1