Fix the breakage due to conflict

src/python/grpcio_tests/tests_aio/unit/server_test.py

@@ -160,7 +160,7 @@ class _GenericHandler(grpc.GenericRpcHandler):
 
     def service(self, handler_details):
         self._called.set_result(None)
-        return self._routing_table[handler_details.method]
+        return self._routing_table.get(handler_details.method)
 
     async def wait_for_call(self):
         await self._called
@@ -395,8 +395,7 @@ class TestServer(AioTestBase):
             await channel.unary_unary(_SIMPLE_UNARY_UNARY)(_REQUEST)
 
     async def test_unimplemented(self):
-        async with aio.insecure_channel(self._server_target) as channel:
-            call = channel.unary_unary(_UNIMPLEMENTED_METHOD)
+        call = self._channel.unary_unary(_UNIMPLEMENTED_METHOD)
         with self.assertRaises(aio.AioRpcError) as exception_context:
             await call(_REQUEST)
         rpc_error = exception_context.exception