Cobra
c012480b7e
on_departure() holds known_lock when calling _check_churn(). When churn threshold is hit, the nested `with known_lock:` inside _check_churn tried to reacquire an already-held non-reentrant lock → permanent deadlock. This killed the production process on the OPi Zero 3 after ~15 hours of runtime on 2026-04-12 at ~02:12 UTC. infrastructure_ips.add() is safe without the inner lock since the caller already holds known_lock. Also: reset _churn_tracker between tests to prevent cross-test state accumulation that triggered the churn threshold in test isolation.