hgext/__init__.py

check-py3-compat: use an absolute path in sys.path

The idea and rationale is similar to https://phab.mercurial-scm.org/D12599
(landed as 1b6e381521c5).

Differential Revision: https://phab.mercurial-scm.org/D12621

from __future__ import absolute_import
import pkgutil

__path__ = pkgutil.extend_path(__path__, __name__)