--- a/mercurial/cmdutil.py	Thu May 30 19:29:03 2013 -0700
+++ b/mercurial/cmdutil.py	Thu May 30 18:47:16 2013 -0700
@@ -1338,7 +1338,7 @@
                 raise util.Abort(_('cannot follow file not in parent '
                                    'revision: "%s"') % f)
             filelog = repo.file(f)
-            if not len(filelog):
+            if not filelog:
                 # A zero count may be a directory or deleted file, so
                 # try to find matching entries on the slow path.
                 if follow: