fix name mangling in generator expressions

Cython/Compiler/Symtab.py

@@ -1351,7 +1351,7 @@ class GeneratorExpressionScope(Scope):
         self.genexp_prefix = "%s%d%s" % (Naming.pyrex_prefix, len(name), name)
 
     def mangle(self, prefix, name):
-        return '%s%s' % (self.genexp_prefix, self.parent_scope.mangle(self, prefix, name))
+        return '%s%s' % (self.genexp_prefix, self.parent_scope.mangle(prefix, name))
 
     def declare_var(self, name, type, pos,
                     cname = None, visibility = 'private', is_cdef = True):