Add __hash__ into CMFCore.Expression.

git-svn-id: https://svn.erp5.org/repos/public/erp5/trunk@1845 20353a03-c40f-0410-a6d1-a30d3c3de9de

product/ERP5Type/ZopePatch.py

@@ -1555,3 +1555,13 @@ ppml.xmlPickler = xmlPickler
 class Tuple(Sequence): pass
 
 ppml.Tuple = Tuple
+
+######################################################################################
+# Expression patch
+
+from Products.CMFCore.Expression import Expression
+
+def Expression_hash(self):
+  return hash(self.text)
+
+Expression.__hash__ = Expression_hash