diff --git a/mercurial/changegroup.py b/mercurial/changegroup.py
--- a/mercurial/changegroup.py
+++ b/mercurial/changegroup.py
@@ -359,7 +359,7 @@ class bundle10(object):
         msgfiles = _('files')
         for i, fname in enumerate(sorted(changedfiles)):
             filerevlog = repo.file(fname)
-            if not len(filerevlog):
+            if not filerevlog:
                 raise util.Abort(_("empty or missing revlog for %s") % fname)
 
             if fastpathlinkrev:
diff --git a/mercurial/cmdutil.py b/mercurial/cmdutil.py
--- a/mercurial/cmdutil.py
+++ b/mercurial/cmdutil.py
@@ -1338,7 +1338,7 @@ def _makegraphlogrevset(repo, pats, opts
                 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: