use getattr on aq_base to prevent acquisition (and not to use hasattr)

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@23972 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5Type/Base.py

@@ -3115,7 +3115,7 @@ class Base( CopyContainer,
         if len(history):
           # Then get the first line of edit_workflow
           return history[0].get('time', None)
-    if hasattr(self, 'CreationDate') :
+    if getattr(aq_base(self), 'CreationDate', None) is not None:
       return asDate(self.CreationDate())
     return None