test_list_subscriptions consistently terminates with UNAVAILABLE and test_fetch_delete_subscription_w_deleted_topic consistently fails self.assertTrue(orphaned.topic is None)

https://travis-ci.org/GoogleCloudPlatform/gcloud-python/builds/154261312
https://travis-ci.org/GoogleCloudPlatform/gcloud-python/builds/154256059
https://travis-ci.org/GoogleCloudPlatform/gcloud-python/builds/154251510

This may be related to #2140. The 3 builds above were the first time this error appeared