add a missing import.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@30669 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5/mixin/property_recordable.py

@@ -28,6 +28,7 @@
 
 import zope.interface
 from AccessControl import ClassSecurityInfo
+from Acquisition import aq_base
 from Products.ERP5Type import Permissions, interfaces
 from Products.ERP5Type.Globals import PersistentMapping