MongoDB result backend: Fixed attribute error for self.app

celery/backends/mongodb.py

@@ -7,6 +7,7 @@ except ImportError:
     pymongo = None
 
 from celery import states
+from celery.app import app_or_default
 from celery.backends.base import BaseDictBackend
 from celery.exceptions import ImproperlyConfigured
 from celery.utils.serialization import pickle
@@ -34,6 +35,7 @@ class MongoBackend(BaseDictBackend):
             module :mod:`pymongo` is not available.
 
         """
+        super(MongoBackend, self).__init__(*args, **kwargs)
         self.result_expires = kwargs.get("result_expires") or \
                                 maybe_timedelta(
                                     self.app.conf.CELERY_TASK_RESULT_EXPIRES)
@@ -59,7 +61,6 @@ class MongoBackend(BaseDictBackend):
             self.mongodb_taskmeta_collection = config.get(
                 "taskmeta_collection", self.mongodb_taskmeta_collection)
 
-        super(MongoBackend, self).__init__(*args, **kwargs)
         self._connection = None
         self._database = None