transaction: do not rely on a global variable to post_finalize file
We can just add a new argument to the `addfilegenerator` function. This is more
explicit and therefor clearer and less error prone.
Differential Revision: https://phab.mercurial-scm.org/D12125
from __future__ import absolute_import
import hashlib
try:
from ..thirdparty import sha1dc # pytype: disable=import-error
sha1 = sha1dc.sha1
except (ImportError, AttributeError):
sha1 = hashlib.sha1