$ git clone -n https://github.com/xcp-ng-rpms/xs-opam-repo /var/lib/mock/v9.0-u-ydi1-11278-29623/root/chroot_tmpdir/scmroot/xs-opam-repo
Cloning into '/var/lib/mock/v9.0-u-ydi1-11278-29623/root/chroot_tmpdir/scmroot/xs-opam-repo'...
$ git fetch origin 4243402d36be5dc598d0432589d09ac7aabee179:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xs-opam-repo
 * [new ref]         4243402d36be5dc598d0432589d09ac7aabee179 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4243402 bump release for test build