$ git clone -n https://github.com/xcp-ng-rpms/libarchive.git /var/lib/mock/v8.3-u-pcoval2-10369-28931/root/chroot_tmpdir/scmroot/libarchive
Cloning into '/var/lib/mock/v8.3-u-pcoval2-10369-28931/root/chroot_tmpdir/scmroot/libarchive'...
$ git fetch origin a5ea3b97663586c21d35d02252ca8c7351291b40:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/libarchive
 * [new ref]         a5ea3b97663586c21d35d02252ca8c7351291b40 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at a5ea3b9 bump release for test build