--- a/mercurial/manifest.py	Tue Apr 21 09:29:59 2015 -0700
+++ b/mercurial/manifest.py	Tue May 05 08:40:59 2015 -0700
@@ -760,7 +760,7 @@
         opts = getattr(opener, 'options', None)
         if opts is not None:
             cachesize = opts.get('manifestcachesize', cachesize)
-            usetreemanifest = opts.get('usetreemanifest', usetreemanifest)
+            usetreemanifest = opts.get('treemanifest', usetreemanifest)
             usemanifestv2 = opts.get('manifestv2', usemanifestv2)
         self._mancache = util.lrucachedict(cachesize)
         revlog.revlog.__init__(self, opener, "00manifest.i")