$ git clone -n https://github.com/xcp-ng-rpms/xs-opam-repo.git /var/lib/mock/v8.3-u-asultanov1-8973-27889/root/chroot_tmpdir/scmroot/xs-opam-repo
Cloning into '/var/lib/mock/v8.3-u-asultanov1-8973-27889/root/chroot_tmpdir/scmroot/xs-opam-repo'...
$ git fetch origin e4bd7ae8dfad86dd9b917da5b805568e4dfa5d62:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xs-opam-repo
 * [new ref]         e4bd7ae8dfad86dd9b917da5b805568e4dfa5d62 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at e4bd7ae test