evas canvas: add exceptional case.

Summary:
parent_container should have eina_false as given null parent
in order to avoid call vg_node_changed() for parent.

Reviewers: #committers, devilhorns, zmike

Reviewed By: #committers, zmike

Subscribers: cedric, #committers, zmike

Tags: #efl

Differential Revision: https://phab.enlightenment.org/D6387

src/lib/evas/canvas/evas_vg_node.c

@@ -351,6 +351,7 @@ _efl_canvas_vg_node_efl_object_parent_set(Eo *obj,
             parent, efl_class_name_get(efl_class_get(parent)), obj);
         return;
      }
+   else parent_container = EINA_FALSE;
 
    if (!_efl_canvas_vg_node_parent_checked_get(obj, &old_parent, &old_cd))
      return;