Recheck the Git behaviour losses accepted in PR #105 #237

When the Git layer was moved back to upstream's code (PR #105, 2026-10-05), three behaviour differences were accepted:

• Hook-finished progress may be missing on Git 2.54, because upstream skips classless child_exit records.
• An unattached merge request branch with local commits can be force-checked-out.
• Auto-pull no longer rechecks ahead/behind under a lock.

Later syncs have taken more upstream Git code since then, so recheck each one against current coder-only and upstream. Close any that no longer apply. File any that are still upstream bugs worth reporting upstream.