revlog: fix error about unknown compression format in py3
In py2, the error is something like:
abort: unknown compression type 'x'!
In py3, we get the following unhelpful message:
abort: unknown compression type <memory at 0x7f4650b5cdc8>!
Switch to something like:
abort: unknown compression type 78!
Differential Revision: https://phab.mercurial-scm.org/D10318
# name space package to host third party extensions
from __future__ import absolute_import
import pkgutil
__path__ = pkgutil.extend_path(__path__, __name__)