mercurial/utils/hashutil.py

delta-find: introduce a base class for _DeltaSearch

This prepare the introduction of specialized the class in the next changesets.

import hashlib

try:
    from ..thirdparty import sha1dc  # pytype: disable=import-error

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