mercurial/utils/hashutil.py

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mercurial/utils/hashutil.py	Mon Jan 13 17:14:19 2020 -0500
@@ -0,0 +1,10 @@
+from __future__ import absolute_import
+
+import hashlib
+
+try:
+    from ..thirdparty import sha1dc
+
+    sha1 = sha1dc.sha1
+except (ImportError, AttributeError):
+    sha1 = hashlib.sha1