use getOb to get the object from zodb

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@10432 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5/Document/BusinessTemplate.py

@@ -584,7 +584,7 @@ class ObjectTemplateItem(BaseTemplateItem):
           subobjects_dict = {}
           # Object already exists
           if object_id in container_ids:
-            old_obj = container[object_id]
+            old_obj = container._getOb(object_id)
             if hasattr(aq_base(old_obj), 'groups'):
               # we must keep original order groups
               # from old form in case we keep some