$ git clone -n https://github.com/xcp-ng-rpms/xs-opam-repo.git /var/lib/mock/v8.3-u-asultanov2-10081-28703/root/chroot_tmpdir/scmroot/xs-opam-repo
Cloning into '/var/lib/mock/v8.3-u-asultanov2-10081-28703/root/chroot_tmpdir/scmroot/xs-opam-repo'...
$ git fetch origin 5cebed470d0b1b010af1fcf68777ed6a54b02acb:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xs-opam-repo
 * [new ref]         5cebed470d0b1b010af1fcf68777ed6a54b02acb -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 5cebed4 bump release for test build