$ git clone -n https://github.com/xcp-ng-rpms/libarchive.git /var/lib/mock/v8.3-u-pcoval2-10390-28952/root/chroot_tmpdir/scmroot/libarchive
Cloning into '/var/lib/mock/v8.3-u-pcoval2-10390-28952/root/chroot_tmpdir/scmroot/libarchive'...
$ git fetch origin 2a9de992a003a3e4de1484e2dc0b4c28d90b6931:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/libarchive
 * [new ref]         2a9de992a003a3e4de1484e2dc0b4c28d90b6931 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 2a9de99 bump release for test build