197068c (#1921) added a per-lot SAVEPOINT around the listings upsert to catch
IntegrityError on UNIQUE(source,source_id) (migration 133) and reconcile via UPDATE.
That's a legit 3rd begin_nested/lot (upsert + snapshot + hook), so the test's
== 2*len(lots) proxy was stale → red main gate blocking all tradein deploys.
Hook itself still opens no inner SAVEPOINT (base.py:715) — test intent preserved.
