--- a/mercurial/revset.py	Fri Nov 28 02:57:33 2014 +0100
+++ b/mercurial/revset.py	Mon Dec 01 05:18:12 2014 -0800
@@ -2804,7 +2804,7 @@
                 pass
             return self.first()
         if self:
-            return it.next()
+            return it().next()
         return None
 
     def last(self):
@@ -2818,7 +2818,7 @@
                 pass
             return self.first()
         if self:
-            return it.next()
+            return it().next()
         return None
 
 def spanset(repo, start=None, end=None):