Merge pull request #9269 from nathanielmanistaatgoogle/v1.0.x-upmerge

src/python/grpcio/grpc/_channel.py

...rpcio_tests/tests/reflection/_reflection_servicer_test.py

src/python/grpcio_tests/tests/tests.json

src/python/grpcio_tests/tests/unit/_compression_test.py

src/python/grpcio_tests/tests/unit/_empty_message_test.py

src/python/grpcio_tests/tests/unit/_exit_scenarios.py

...ython/grpcio_tests/tests/unit/_invocation_defects_test.py

src/python/grpcio_tests/tests/unit/_metadata_test.py