diff -r 8f9f542622d9 -r 39c1ffc7d93f server/schemaserial.py
--- a/server/schemaserial.py	Thu Mar 31 09:39:51 2011 +0200
+++ b/server/schemaserial.py	Thu Mar 31 15:23:46 2011 +0200
@@ -1,4 +1,4 @@
-# copyright 2003-2010 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
+# copyright 2003-2011 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
 # contact http://www.logilab.fr/ -- mailto:contact@logilab.fr
 #
 # This file is part of CubicWeb.
@@ -564,7 +564,7 @@
                 yield ('INSERT RQLExpression E: E expression %%(e)s, E exprtype %%(t)s, '
                        'E mainvars %%(v)s, X %s_permission E WHERE X eid %%(x)s' % action,
                        {'e': unicode(rqlexpr.expression),
-                        'v': unicode(rqlexpr.mainvars),
+                        'v': unicode(','.join(sorted(rqlexpr.mainvars))),
                         't': unicode(rqlexpr.__class__.__name__)})
 
 # update functions