dry_upgrade_changes_lockfile called ensure_read_clone (which syncs the
read clone under the _meta-conventions lock then releases it) and ran
'git clone --local --no-hardlinks <read_clone>' OUTSIDE the lock. A
concurrent ensure_read_clone -> _sync_read_clone (fetch + hard-reset to
origin's default branch) could mutate the read clone's working tree /
object db mid-clone, racing the clone and producing an inconsistent or
failing probe.
Split _probe_lockfile_change into _clone_local_into (the local clone,
run under the read-clone lock) + _probe_lockfile_on_clone (the upgrade +
git status, run without the lock on the now-independent copy). The probe
acquires _ensure_lock_for(slug, '_meta-conventions') — the same lock
ensure_read_clone syncs under — and holds it only for the clone step; the
upgrade operates on the full --no-hardlinks copy and never touches the
read clone, so the lock is released before it to avoid blocking
conventions reads for the upgrade duration.
The tiny gap between ensure_read_clone releasing the lock and the probe
re-acquiring it is safe: any concurrent _sync_read_clone completes under
the lock before the probe acquires, so the clone reads a stable state.
Renn F
1a773e45d7