$ git clone -n https://github.com/xcp-ng-rpms/xs-opam-repo.git /var/lib/mock/v8.3-u-pcoval2-10447-29007/root/chroot_tmpdir/scmroot/xs-opam-repo
Cloning into '/var/lib/mock/v8.3-u-pcoval2-10447-29007/root/chroot_tmpdir/scmroot/xs-opam-repo'...
$ git fetch origin b278b1e0e5e0eceaa1e32de896dae6304c89a5c5:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xs-opam-repo
 * [new ref]         b278b1e0e5e0eceaa1e32de896dae6304c89a5c5 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b278b1e bump release for test build