Ticket #10249: 10249.diff

django/db/models/fields/files.py

@@ -136 +136 @@
             # have the FieldFile interface added to them
             file_copy = copy.copy(file)
             file_copy.__class__ = type(file.__class__.__name__, 
-                                       (file.__class__, self.field.attr_class), {})
+                                       (self.field.attr_class, file.__class__), {})
             file_copy.instance = instance
             file_copy.field = self.field
             file_copy.storage = self.field.storage