Remove fallback retarget, add debugging for auto-retarget

Instead of silently falling back to manual retarget when GitHub's
auto-retarget doesn't trigger, fail with debug info to understand
the root cause.

Author: claude

tests/test_e2e.sh

@@ -564,15 +564,23 @@ echo >&2 "0d. Merging NoAct PR1 (without action installed)..."
 merge_pr_with_retry "$NOACT_PR1_URL"
 echo >&2 "NoAct PR1 merged. Branch should be auto-deleted and PR2 auto-retargeted."
 
-# Wait for GitHub to auto-retarget PR2 to main, or manually retarget if needed
-if ! wait_for_pr_base_change "$NOACT_PR2_NUM" "main" 5; then
-    # GitHub's auto-retarget didn't trigger, manually retarget
-    echo >&2 "Auto-retarget didn't occur, manually retargeting PR2 to main..."
-    log_cmd gh pr edit "$NOACT_PR2_NUM" --repo "$REPO_FULL_NAME" --base main
-    if ! wait_for_pr_base_change "$NOACT_PR2_NUM" "main" 5; then
-        echo >&2 "❌ Failed to retarget PR2 to main"
-        exit 1
-    fi
+# Debug: Check if the branch was actually deleted
+echo >&2 "Checking if noact_feature1 branch was deleted..."
+if gh api "/repos/$REPO_FULL_NAME/branches/noact_feature1" &>/dev/null; then
+    echo >&2 "❌ Branch noact_feature1 still exists! Auto-delete may not have worked."
+    echo >&2 "Repo settings:"
+    gh api "/repos/$REPO_FULL_NAME" --jq '{delete_branch_on_merge}' >&2
+    exit 1
+else
+    echo >&2 "✅ Branch noact_feature1 was deleted."
+fi
+
+# Wait for GitHub to auto-retarget PR2 to main
+if ! wait_for_pr_base_change "$NOACT_PR2_NUM" "main"; then
+    echo >&2 "❌ GitHub did not auto-retarget PR2 to main"
+    echo >&2 "Debug info:"
+    gh pr view "$NOACT_PR2_NUM" --repo "$REPO_FULL_NAME" --json baseRefName,state,headRefName >&2
+    exit 1
 fi
 
 # Capture diff after retarget