'test_list_topics: failure during teardown

[tseaver]

From: https://travis-ci.org/GoogleCloudPlatform/gcloud-python/builds/154249353#L800-L826

======================================================================
ERROR: test_list_topics (pubsub.TestPubsub)
----------------------------------------------------------------------
Traceback (most recent call last):
 File "/home/travis/build/GoogleCloudPlatform/gcloud-python/system_tests/pubsub.py", line 61, in tearDown
 doomed.delete()
 File "/home/travis/build/GoogleCloudPlatform/gcloud-python/.tox/system-tests/lib/python2.7/site-packages/gcloud/pubsub/topic.py", line 203, in delete
 api.topic_delete(topic_path=self.full_name)
 File "/home/travis/build/GoogleCloudPlatform/gcloud-python/.tox/system-tests/lib/python2.7/site-packages/gcloud/pubsub/_gax.py", line 130, in topic_delete
 self._gax_api.delete_topic(topic_path)
 File "/home/travis/build/GoogleCloudPlatform/gcloud-python/.tox/system-tests/lib/python2.7/site-packages/google/cloud/pubsub/v1/publisher_api.py", line 403, in delete_topic
 self._delete_topic(request, options)
 File "/home/travis/build/GoogleCloudPlatform/gcloud-python/.tox/system-tests/lib/python2.7/site-packages/google/gax/api_callable.py", line 480, in inner
 return api_caller(api_call, this_settings, request)
 File "/home/travis/build/GoogleCloudPlatform/gcloud-python/.tox/system-tests/lib/python2.7/site-packages/google/gax/api_callable.py", line 468, in base_caller
 return api_call(*args)
 File "/home/travis/build/GoogleCloudPlatform/gcloud-python/.tox/system-tests/lib/python2.7/site-packages/google/gax/api_callable.py", line 433, in inner
 raise_with_traceback(GaxError('RPC failed', cause=exception))
 File "/home/travis/build/GoogleCloudPlatform/gcloud-python/.tox/system-tests/lib/python2.7/site-packages/google/gax/api_callable.py", line 430, in inner
 return a_func(*args, **kwargs)
 File "/home/travis/build/GoogleCloudPlatform/gcloud-python/.tox/system-tests/lib/python2.7/site-packages/google/gax/api_callable.py", line 64, in inner
 return a_func(*updated_args, **kwargs)
 File "/home/travis/build/GoogleCloudPlatform/gcloud-python/.tox/system-tests/lib/python2.7/site-packages/grpc/beta/_client_adaptations.py", line 305, in __call__
 self._request_serializer, self._response_deserializer)
 File "/home/travis/build/GoogleCloudPlatform/gcloud-python/.tox/system-tests/lib/python2.7/site-packages/grpc/beta/_client_adaptations.py", line 203, in _blocking_unary_unary
 raise _abortion_error(rpc_error_call)
GaxError: GaxError(RPC failed, caused by AbortionError(code=StatusCode.INTERNAL, details="Internal error encountered."))
``

[tseaver]

I'm going to put on my Pollyanna/Candide hat and claim that #2195 has resolved this issue.