diff -r 3a0d91237e2c -r c4aa23af0baa hooks/syncschema.py
--- a/hooks/syncschema.py	Thu Mar 21 16:52:13 2013 +0100
+++ b/hooks/syncschema.py	Thu Mar 28 12:32:26 2013 +0100
@@ -507,6 +507,8 @@
 
     def revertprecommit_event(self):
         # revert changes on in memory schema
+        if getattr(self, 'rdefdef', None) is None:
+            return
         self.session.vreg.schema.del_relation_def(
             self.rdefdef.subject, self.rdefdef.name, self.rdefdef.object)
         # XXX revert changes on database