$ git clone -n https://github.com/xcp-ng-rpms/libarchive /var/lib/mock/v8.3-incoming-9161-27982/root/chroot_tmpdir/scmroot/libarchive
Cloning into '/var/lib/mock/v8.3-incoming-9161-27982/root/chroot_tmpdir/scmroot/libarchive'...
$ git fetch origin 247331deee0b169e1e746d39e5f231923f0d6c8a:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/libarchive
 * [new ref]         247331deee0b169e1e746d39e5f231923f0d6c8a -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 247331d Refresh ldconfig cache on installation/removal