revlog: add the appropriate flag is sidedata are passed to `addrevision`
If we need to store sidedata, we need the flag to be set and the associated
processing to be called.
Differential Revision: https://phab.mercurial-scm.org/D6894
# name space package to host third party extensions
from __future__ import absolute_import
import pkgutil
__path__ = pkgutil.extend_path(__path__, __name__)