diff -r fdd7f614ca2a -r 7fc54e02291f schema.py
--- a/schema.py	Thu Oct 03 15:37:45 2013 +0200
+++ b/schema.py	Tue Oct 08 16:10:42 2013 +0200
@@ -702,6 +702,8 @@
                              'expression %s', mainvar, self)
         # syntax tree used by read security (inserted in queries when necessary)
         self.snippet_rqlst = parse(self.minimal_rql, print_errors=False).children[0]
+        # graph of links between variables, used by rql rewriter
+        self.vargraph = vargraph(self.rqlst)
 
     def __str__(self):
         return self.full_rql
@@ -909,8 +911,6 @@
         if mainvars is None:
             mainvars = guess_rrqlexpr_mainvars(expression)
         RQLExpression.__init__(self, expression, mainvars, eid)
-        # graph of links between variable, used by rql rewriter
-        self.vargraph = vargraph(self.rqlst)
 
     @property
     def full_rql(self):