revset: move weight information to predicate
Previously revset weight is hardcoded and cannot be modified. This patch
moves it to predicate so newly registered revsets could define their weight
to properly give static optimization some hint.
Differential Revision: https://phab.mercurial-scm.org/D657
from __future__ import absolute_import
import pkgutil
__path__ = pkgutil.extend_path(__path__, __name__)