Fix a six.with_metaclass usage mistake

nathanielmanistaatgoogle · nathanielmanistaatgoogle · commit 86eb4ec0ef68 · 2017-09-18T14:22:16.000Z
I made this mistake in 2010985 but only with yesterday's release of six 1.11.0 has it started failing ("TypeError: metaclass conflict: the metaclassof a derived class must be a (non-strict) subclass of the metaclasses of all its bases").
diff --git a/src/python/grpcio_testing/grpc_testing/__init__.py b/src/python/grpcio_testing/grpc_testing/__init__.py
@@ -213,7 +213,7 @@ def terminate(self, trailing_metadata, code, details):
         raise NotImplementedError()
 
 
-class Channel(six.with_metaclass(abc.ABCMeta), grpc.Channel):
+class Channel(six.with_metaclass(abc.ABCMeta, grpc.Channel)):
     """A grpc.Channel double with which to test a system that invokes RPCs."""
 
     @abc.abstractmethod
