Fix a bug where worktree creation would apply to nested git repos (#53771)

Saw this while manually testing other stuff.

Self-Review Checklist:

- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content is consistent with the [UI/UX
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
- [x] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable

Release Notes:

- N/A
8e0005c0cdMikayla Maki committed on 4/13/2026, 6:04:46 AM· committed by GitHubparentc512c72
1 file changedLine totals unavailable