[#368] Use the correct schema to validate against in controllers.grou…

…p.history

ckan/controllers/group.py

@@ -671,7 +671,7 @@ def history(self, id):
 
         context = {'model': model, 'session': model.Session,
                    'user': c.user or c.author,
-                   'schema': self._form_to_db_schema()}
+                   'schema': self._db_to_form_schema()}
         data_dict = {'id': id}
         try:
             c.group_dict = self._action('group_show')(context, data_dict)