95d8d8056d
Problem: --depth=1 fetch does not bring in the PR head branch name as a ref, causing 'origin/gandalf/pri-1593-fix-main' to be unknown. Fix: fetch all PR head refs with full refspec and diff against HEAD instead of a non-existent remote branch ref. Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>