See: https://circleci.com/gh/GoogleCloudPlatform/google-cloud-python/1781 [Failed line][1] assumes `operation.results` will be a list, but instead it is `None`. [1]: https://github.com/GoogleCloudPlatform/google-cloud-python/blob/391c6fd807f5f4c0ea7066ec086cfa67b47a637e/speech/tests/system.py#L188