Topology not garbage collected during test_encryption.TestDataKeyDoubleEncryption

Topology <Topology <TopologyDescription id: 5fa1f0698ad53cb215fa7405, topology_type: ReplicaSetWithPrimary, servers: [<ServerDescription ('localhost', 27017) server_type: RSPrimary, rtt: 0.000538420648610058>, <ServerDescription ('localhost', 27018) server_type: RSSecondary, rtt: 0.001056252019849808>, <ServerDescription ('localhost', 27019) server_type: RSArbiter, rtt: 0.0009123198919968762>]>> has THREADS RUNNING: [<PeriodicExecutor(name=pymongo_server_monitor_thread) object at 0x7ff450e41a90>, <PeriodicExecutor(name=pymongo_server_rtt_thread) object at 0x7ff450e41a50>, <PeriodicExecutor(name=pymongo_server_monitor_thread) object at 0x7ff450bfb350>, <PeriodicExecutor(name=pymongo_server_rtt_thread) object at 0x7ff450bfb250>, <PeriodicExecutor(name=pymongo_server_monitor_thread) object at 0x7ff450bfbc10>, <PeriodicExecutor(name=pymongo_server_rtt_thread) object at 0x7ff4524dbbd0>], created at:   File "setup.py", line 431, in <module>

  **extra_opts

File "/data/mci/1d06ce731bf44d878db71873b3380fd4/src/venv-encryption/lib/python3.7/site-packages/setuptools/__init__.py", line 153, in setup

  return distutils.core.setup(**attrs)

File "/opt/python/3.7/lib/python3.7/distutils/core.py", line 148, in setup

  dist.run_commands()

File "/opt/python/3.7/lib/python3.7/distutils/dist.py", line 966, in run_commands

  self.run_command(cmd)

File "/opt/python/3.7/lib/python3.7/distutils/dist.py", line 985, in run_command

  cmd_obj.run()

File "setup.py", line 130, in run

  result = runner.run(suite)

File "/data/mci/1d06ce731bf44d878db71873b3380fd4/src/test/__init__.py", line 874, in run

  result = super(PymongoXMLTestRunner, self).run(test)

File "/opt/python/3.7/lib/python3.7/site-packages/xmlrunner/runner.py", line 66, in run

  test(result)

File "/opt/python/3.7/lib/python3.7/unittest/suite.py", line 84, in __call__

  return self.run(*args, **kwds)

File "/opt/python/3.7/lib/python3.7/unittest/suite.py", line 114, in run

  self._handleClassSetUp(test, result)

File "/opt/python/3.7/lib/python3.7/unittest/suite.py", line 163, in _handleClassSetUp

  setUpClass()

File "/data/mci/1d06ce731bf44d878db71873b3380fd4/src/test/test_encryption.py", line 630, in setUpClass

  cls.client = rs_or_single_client(event_listeners=[cls.listener])

File "/data/mci/1d06ce731bf44d878db71873b3380fd4/src/test/utils.py", line 500, in rs_or_single_client

  return _mongo_client(h, p, **kwargs)

File "/data/mci/1d06ce731bf44d878db71873b3380fd4/src/test/utils.py", line 461, in _mongo_client

  **client_options)

File "/data/mci/1d06ce731bf44d878db71873b3380fd4/src/pymongo/mongo_client.py", line 727, in __init__

  direct_connection=options.direct_connection)

File "/data/mci/1d06ce731bf44d878db71873b3380fd4/src/pymongo/settings.py", line 72, in __init__

  self._stack = ''.join(traceback.format_stack())