AMQP results: Results exchange must not be auto_delete (backward incompatible change)

celery/backends/amqp.py

@@ -55,7 +55,7 @@ class AMQPBackend(BaseDictBackend):
                                       type=exchange_type,
                                       delivery_mode=delivery_mode,
                                       durable=self.persistent,
-                                      auto_delete=auto_delete)
+                                      auto_delete=False)
         self.serializer = serializer or conf.CELERY_RESULT_SERIALIZER
         self.auto_delete = auto_delete