hgext/__init__.py

rust-python3: useless python2 specific import

This python27_sys import prevents building with python3,
it had been previously removed in a5fa9140ce4c, but that
has been since pruned

Differential Revision: https://phab.mercurial-scm.org/D6415

from __future__ import absolute_import
import pkgutil
__path__ = pkgutil.extend_path(__path__, __name__)