commit: look-up new revision once Look-up by node is slightly more expensive, so since it is necessary more than once, do it explicitly. Differential Revision: https://phab.mercurial-scm.org/D9830

from __future__ import absolute_import

import hashlib

try:
    from ..thirdparty import sha1dc

    sha1 = sha1dc.sha1
except (ImportError, AttributeError):
    sha1 = hashlib.sha1