Drop orphan test.

Closes: #2080.

system_tests/pubsub.py

@@ -262,40 +262,3 @@ def test_subscription_iam_policy(self):
             policy.viewers.add(policy.user('jjg@google.com'))
             new_policy = subscription.set_iam_policy(policy)
             self.assertEqual(new_policy.viewers, policy.viewers)
-
-    # This test is ultra-flaky.  See:
-    # https://github.com/GoogleCloudPlatform/google-cloud-python/issues/2080
-    @unittest.expectedFailure
-    def test_fetch_delete_subscription_w_deleted_topic(self):
-        from google.cloud.iterator import MethodIterator
-        TO_DELETE = 'delete-me' + unique_resource_id('-')
-        ORPHANED = 'orphaned' + unique_resource_id('-')
-        topic = Config.CLIENT.topic(TO_DELETE)
-        topic.create()
-        subscription = topic.subscription(ORPHANED)
-        subscription.create()
-        topic.delete()
-
-        def _fetch():
-            return list(MethodIterator(Config.CLIENT.list_subscriptions))
-
-        def _found_orphan(result):
-            names = [subscription.name for subscription in result]
-            return ORPHANED in names
-
-        retry_until_found_orphan = RetryResult(_found_orphan)
-        all_subs = retry_until_found_orphan(_fetch)()
-
-        created = [subscription for subscription in all_subs
-                   if subscription.name == ORPHANED]
-        self.assertEqual(len(created), 1)
-        orphaned = created[0]
-        self.to_delete.append(orphaned)
-
-        def _no_topic(instance):
-            return instance.topic is None
-
-        retry_until_no_topic = RetryInstanceState(_no_topic)
-        retry_until_no_topic(orphaned.reload)()
-
-        self.assertTrue(orphaned.topic is None)