$ git clone -n https://github.com/xcp-ng-rpms/xs-opam-repo.git /var/lib/mock/v8.3-u-asultanov2-9022-27913/root/chroot_tmpdir/scmroot/xs-opam-repo
Cloning into '/var/lib/mock/v8.3-u-asultanov2-9022-27913/root/chroot_tmpdir/scmroot/xs-opam-repo'...
$ git fetch origin a7650e2c55bcb41fa7e6f4bc24d69581cda0563e:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xs-opam-repo
 * [new ref]         a7650e2c55bcb41fa7e6f4bc24d69581cda0563e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at a7650e2 bump release for test build