many bugfixes related to fast_parser

jedi/helpers.py

@@ -166,7 +166,7 @@ def fast_parent_copy(obj):
                     setattr(new_obj, key, new_elements[value])
                 except KeyError:
                     pass
-            elif key in ['parent_stmt', 'parent_function']:
+            elif key in ['parent_stmt', 'parent_function', 'set_parent']:
                 continue
             elif isinstance(value, list):
                 setattr(new_obj, key, list_rec(value))