minor fix, refs 3aef427

Author: wwwjfy

gino/api.py

@@ -503,4 +503,4 @@ def __getattribute__(self, item):
     def __setattr__(self, key, value):
         if key == '_exception':
             return super().__setattr__(key, value)
-        raise UninitializedError(self._exception)
+        raise self._exception