Ticket #15282: patch.diff

django/forms/models.py

@@ -213 +213 @@
                 message = message % (', '.join(missing_fields),
                                      opts.model.__name__)
                 raise FieldError(message)
+            
+            if parents:
+                for parent in parents:
+                    if parent is not ModelForm:
+                        fields.update(parent.base_fields)
+            
             # Override default model fields with any custom declared ones
             # (plus, include all the other declared fields).
             fields.update(declared_fields)