pass using to index_queryset for update

Author: bigjust

haystack/indexes.py

@@ -255,7 +255,7 @@ def update(self, using=None):
         backend = self._get_backend(using)
 
         if backend is not None:
-            backend.update(self, self.index_queryset())
+            backend.update(self, self.index_queryset(using=using))
 
     def update_object(self, instance, using=None, **kwargs):
         """