do not overload full dict when key not found

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@16023 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5Type/Base.py

@@ -2216,7 +2216,7 @@ class Base( CopyContainer,
         if property_dict.get(k, None) is not None:
           property_dict[k].update(user_dict[k])
         else:
-          property_dict.update(user_dict)
+          property_dict[k] = user_dict[k]
     return property_dict