test_add_distributed_object_listener_object_destroyed

The `test_add_distributed_object_listener_object_destroyed` failed on the PR builder.

It seems that the `DESTROYED` event is not received.

```
16:12:18 ======================================================================
16:12:18 ERROR: test_add_distributed_object_listener_object_destroyed (tests.proxy.distributed_objects_test.DistributedObjectsTest)
16:12:18 ----------------------------------------------------------------------
16:12:18 Traceback (most recent call last):
16:12:18 File "/home/jenkins/jenkins_slave/workspace/python3.7-pr-builder/tests/proxy/distributed_objects_test.py", line 77, in test_add_distributed_object_listener_object_destroyed
16:12:18 self.assertTrueEventually(assert_event)
16:12:18 File "/home/jenkins/jenkins_slave/workspace/python3.7-pr-builder/tests/base.py", line 64, in assertTrueEventually
16:12:18 raise
16:12:18 RuntimeError: No active exception to reraise
```

http://jenkins.hazelcast.com/job/python3.7-pr-builder/183/

Beginne mit test_add_distributed_object_listener_object_destroyed in tests/proxy/distributed_objects_test.py und der assertTrueEventually-Hilfsfunktion in tests/base.py. Reproduziere den Fehler im Python 3.7 PR builder und verfolge, warum das DESTROYED-Ereignis nicht empfangen wird. Erledigt ist die Aufgabe, wenn der Test das Ereignis zuverlässig empfängt und erfolgreich durchläuft.

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