IngestorManager.__del__ calls asyncio.run(self.shutdown()). Adding
tests/unit/connection/test_pool.py shifted GC timing enough that a
cyclic-referenced IngestorManager instance from an earlier test was
swept mid test___del__, double-calling the patched asyncio mock and
failing the assertion. Deterministic gc.collect() after each test in
this file keeps finalizers scoped to their own test.
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