a quick replacement of /usr/lib/pymodules/python2.6/tracext/hg/backend.py with http://trac.edgewall.org/browser/plugins/0.11/mercurial-plugin/tracext/hg/backend.py?rev=9601 fixed the problem.
a quick replacement of /usr/lib/ pymodules/ python2. 6/tracext/ hg/backend. py with http:// trac.edgewall. org/browser/ plugins/ 0.11/mercurial- plugin/ tracext/ hg/backend. py?rev= 9601 fixed the problem.