+++ This bug was initially created as a clone of Bug #1042640 +++

git from 2.13.0 started using a hardened SHA1 implementation with can detect
one side of a SHA1 collision generated using cryptanalytic attacks.

The implementation was taken from
https://github.com/cr-marcstevens/sha1collisiondetection
It is currently bundled in the upstream git tree:
https://github.com/git/git/commits/master/sha1dc

https://github.com/git/git/commit/2281b8a36288a13ba17eb908ee7be366843c84f5
https://github.com/git/git/commit/e6b07da2780f349c29809bd75d3eca6ad3c35d19
https://github.com/git/git/commit/8325e43b82dd0bd00c37abed45861bb8c155b022

It is also the default SHA1 implementation, so git 2.13.0 no longer links
against openSSL for SHA1.

We have this code in a separate library package in Tumbleweed and from openSUSE
Leap 42.3. Should be unbundled in git to use the system library:

sha1collisiondetection
libsha1detectcoll1
libsha1detectcoll-devel