[dependabot:release-train-updater] Systemic create_pull_request safe-output failure blocking `@github/copilot-sdk` 1.0.11→1.0.13 dependency bump (8 consecutive run

## Summary

The `dependabot-release-train-updater` worker has attempted the same routine patch bump of `@github/copilot-sdk` from `1.0.11` to `1.0.13` across **8 consecutive runs** (2026-09-08 03:36 through 14:34 UTC, plus earlier runs) and every attempt fails at the `create_pull_request` safe-output call with the same error:

```
No changes to commit - no commits found
```

**Action:** A maintainer with access to the safe-outputs/gh-aw runtime should investigate why `create_pull_request` reports no commits despite a verified-correct git state. Acceptance check: the next automated run of this worker successfully opens a PR for this bump (or any bump) without manual intervention.

## Evidence this is not a caller-side git-state issue

Each run (including this one) independently verified before calling the tool:
- Fresh branch created off latest `origin/main`
- `package.json` and `package-lock.json` diffs present and non-trivial (this run: 88 insertions / 105 deletions in `package-lock.json`, 1 line in `package.json`)
- Changes staged with `git add` and committed with `git commit` (this run's commit: `6b63a328540c3a74810643bc3dbbd365ec62c193`)
- `git log origin/main..HEAD` confirmed exactly 1 commit ahead of the base
- `git status` confirmed a clean working tree post-commit
- Correct branch (`dependabot-agent/npm-copilot-sdk-1.0.13-v3` this run) was checked out and passed as the `branch` parameter

Despite this, `create_pull_request` returned the same "no commits found" error every time, across multiple distinct branch names and commit SHAs over roughly 12 hours of runs (see repository dependency-agent cache memory, files `dependabot-release-train-2026-09-08-*.md`, for the full history of this recurring failure signature).

Prior escalation history

- 6 consecutive identical failures were logged in cache memory before this issue, with the most recent prior run (2026-09-08 13:33) calling `missing_tool` to flag the defect and recommending future runs check whether it's fixed before retrying.
- This run retried once (per the "at most 2 recovery approaches" retry policy) with a completely fresh branch/commit to rule out any leftover state, got the identical error, and is now escalating via `create_issue` as recommended.

## Recommended next step

- Investigate the `create_pull_request` safe-output handler/action for this repository's workflow configuration — possible causes include a stale base-SHA comparison, a misconfigured push step, or a permissions/branch-protection issue specific to this worker's PR title prefix (`[dependabot-agent] `).
- Until fixed, automated attempts to open this specific dependency PR should be paused to avoid redundant work; the dependency bump itself (`@github/copilot-sdk` 1.0.11 → 1.0.13, patch-level, reachable via `dashboard/local-server.mjs`) is low-risk and ready to merge once tooling is repaired — the verified diff is described above and can be reproduced with:
```
npm install @github/copilot-sdk@1.0.13 --save-exact --package-lock-only
```

### Control Plane
- Correlation ID: 34238071936-137
- Central repo: githubnext/gh-aw-cao
- Run URL: https://github.com/githubnext/gh-aw-cao/actions/runs/34238071936

> Generated by [:dependabot: Dependabot / Release Trains](https://github.com/githubnext/gh-aw-cao/actions/runs/34238532178) · copilot · auto · 55 AIC · ⌖ 8.97 AIC · ⊞ 20.5K · [◷](https://github.com/search?q=repo%3Agithubnext%2Fgh-aw-cao+is%3Aissue+%22gh-aw-workflow-call-id%3A+githubnext%2Fgh-aw-cao%2Fdependabot-release-train-updater%22&type=issues)
>

_{Add this agentic workflow to your repo}

To install this agentic workflow, run

```
gh aw add githubnext/gh-aw-cao/.github/workflows/dependabot-release-train-updater.md@main
```

> - [x] expires on Sep 22, 2026, 2:37 PM UTC

Start with the dependabot-release-train-updater workflow configuration and the create_pull_request safe-output handler, then review the repeated failure records in the dependabot-release-train-2026-09-08-*.md cache files. Reproduce the dependency update from dashboard/local-server.mjs with npm install, inspect the branch and commit inputs, and verify that a subsequent automated run opens the pull request without manual intervention.

Written by the indexing model from the issue text.