Fix kombu.messaging.Consumer.__exit__, which didn’t conform to PEP 0343’s calling convention, and thus rendered Consumer unusable in a with statement.

kombu/messaging.py

@@ -256,8 +256,9 @@ class Consumer(object):
         self.consume()
         return self
 
-    def __exit__(self):
+    def __exit__(self, exc_type, exc_val, traceback):
         self.cancel()
+        return False
 
     def consume(self, no_ack=None):
         """Register consumer on server.

kombu/tests/test_messaging.py

@@ -217,7 +217,9 @@ class test_Consumer(unittest.TestCase):
         context = consumer.__enter__()
         self.assertIs(context, consumer)
         self.assertTrue(consumer._active_tags)
-        consumer.__exit__()
+        self.assertRaises(TypeError, consumer.__exit__)
+        res = consumer.__exit__(None, None, None)
+        self.assertFalse(res)
         self.assertIn("basic_cancel", channel)
         self.assertFalse(consumer._active_tags)