When multiple polecats run bd sync simultaneously, they race to push to
the shared beads-sync branch. Previously this caused non-fast-forward
errors that blocked all polecats.
Now pushFromWorktree:
- Detects non-fast-forward errors from git push output
- On conflict: fetches remote, rebases local commits on top, retries
- Uses exponential backoff for transient failures (up to 5 retries)
- Aborts rebase cleanly if it fails to leave worktree in good state
Fixes gt-zqor.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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