diff --git a/rhodecode/lib/graphmod.py b/rhodecode/lib/graphmod.py
--- a/rhodecode/lib/graphmod.py
+++ b/rhodecode/lib/graphmod.py
@@ -1,3 +1,16 @@
+# -*- coding: utf-8 -*-
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
 """
 Modified mercurial DAG graph functions that re-uses VCS structure
 
@@ -36,7 +49,7 @@ def _dagwalker(repo, revs, alias):
         repo = repo
     elif alias == 'git':
         def cl(rev):
-            return [x.revision for x in repo[rev].parents()]
+            return [x.revision for x in repo[rev].parents]
         repo = repo
 
     lowestrev = min(revs)