py3: test*gendoc*.t passes on Python 3
The buildbot didn't notice because docutils isn't installed in Python
3 there yet. I verified this locally.
Differential Revision: https://phab.mercurial-scm.org/D5617
# name space package to host third party extensions
from __future__ import absolute_import
import pkgutil
__path__ = pkgutil.extend_path(__path__, __name__)