$ git clone -n https://github.com/xcp-ng-rpms/xs-opam-repo.git /var/lib/mock/v8.3-u-asultanov2-10326-28890/root/chroot_tmpdir/scmroot/xs-opam-repo
Cloning into '/var/lib/mock/v8.3-u-asultanov2-10326-28890/root/chroot_tmpdir/scmroot/xs-opam-repo'...
$ git fetch origin d27610892f1f6335ba6253b9b889c542272b699d:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xs-opam-repo
 * [new ref]         d27610892f1f6335ba6253b9b889c542272b699d -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at d276108 bump release for test build