$ git clone -n https://github.com/xcp-ng-rpms/xs-opam-repo.git /var/lib/mock/v8.3-u-pcoval2-10439-29000/root/chroot_tmpdir/scmroot/xs-opam-repo
Cloning into '/var/lib/mock/v8.3-u-pcoval2-10439-29000/root/chroot_tmpdir/scmroot/xs-opam-repo'...
$ git fetch origin a350152b60c0011a00b5f0bea522229db44701fd:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xs-opam-repo
 * [new ref]         a350152b60c0011a00b5f0bea522229db44701fd -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at a350152 bump release for test build