ci: fix existing-PR detection for cross-fork promotion

[herikwebb]

Bug

The re-run of Promote to upstream failed with a pull request for branch "…" into branch "main" already exists … Error: exit code 1. The idempotency check used gh pr list --repo <upstream> --head <owner:branch>, which does not reliably match a cross-fork head on the base repo — so existing came back empty, the job fell through to gh pr create, and GitHub rejected the duplicate.

Fix

Query the REST pulls head filter directly (GET /repos/{upstream}/pulls?head=user:branch&state=open), and gh pr edit the matched PR number. This correctly detects the open cross-fork PR (plmbr#386) and refreshes its title/body instead of trying to recreate it.

---

Generated by Claude Code

[github-actions]

Automated PR Review

Model: gpt-5.5
Verdict: CHANGES_REQUESTED

Changed files:

.github/workflows/promote-upstream.yml

Review result:

Findings

Medium — .github/workflows/promote-upstream.yml — Existing PR lookup no longer scopes by requested base branch

The new REST lookup checks only:

-f head="${head_ref}" -f state=open

but no longer includes the requested BASE. This can match an open PR from the same fork branch targeting a different upstream base branch. In that case the workflow will edit that unrelated PR and exit successfully instead of creating/updating the PR for the requested base branch.

This is especially relevant because base is a workflow input and the previous implementation explicitly scoped by --base "${BASE}".

Suggested fix:

existing_num="$(gh api -X GET "repos/${UPSTREAM}/pulls" \
  -f head="${head_ref}" -f base="${BASE}" -f state=open --jq '.[0].number // ""')"