diff -r b08af8f0ac01 -r fafd9a1284cf mercurial/revset.py
--- a/mercurial/revset.py	Wed Oct 01 20:26:33 2014 -0400
+++ b/mercurial/revset.py	Mon Feb 02 22:21:07 2015 +0900
@@ -2448,7 +2448,9 @@
         tree = findaliases(ui, tree, showwarning=ui.warn)
     tree = foldconcat(tree)
     weight, tree = optimize(tree, True)
-    def mfunc(repo, subset):
+    def mfunc(repo, subset=None):
+        if subset is None:
+            subset = spanset(repo)
         if util.safehasattr(subset, 'isascending'):
             result = getset(repo, subset, tree)
         else: