can this test expand its upper and lower bounds here? i believe i have had this fail on me once before as well, and since the error is about receiving 3 instead of 4-6 messages, this seems like prime flakiness material. any approach to more robustly test this sort of ipc seems like it could be dealt with at least partially in a similar way to any code that e.g. retries network requests (and there's no reason this code would need to only be usable in tests). https://travis-ci.org/pantsbuild/pants/jobs/461128648 (i'm going to restart this build soon though):

_ TestProcessMetadataManager.test_deadline_until _
                     
                     self = <pants_test.pantsd.test_process_manager.TestProcessMetadataManager testMethod=test_deadline_until>
                     
                         def test_deadline_until(self):
                           with self.assertRaises(ProcessMetadataManager.Timeout):
                             with self.captured_logging(<http://logging.INFO|logging.INFO>) as captured:
                               self.pmm._deadline_until(lambda: False, 'the impossible', timeout=.5, info_interval=.1)
                           self.assertTrue(4 <= len(captured.infos()) <= 6,
                     >                     'Expected between 4 and 6 infos, got: {}'.format(captured.infos()))
                     E     AssertionError: False is not true : Expected between 4 and 6 infos, got: ['pants.pantsd.process_manager: waiting for the impossible...', 'pants.pantsd.process_manager: waiting for the impossible...', 'pants.pantsd.process_manager: waiting for the impossible...']