$ git clone -n https://github.com/xcp-ng-rpms/xs-opam-repo.git /var/lib/mock/v8.3-u-asultanov2-9002-27903/root/chroot_tmpdir/scmroot/xs-opam-repo
Cloning into '/var/lib/mock/v8.3-u-asultanov2-9002-27903/root/chroot_tmpdir/scmroot/xs-opam-repo'...
$ git fetch origin 0a6f0f63fd493d3a064008ab3980fe4be55c3001:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xs-opam-repo
 * [new ref]         0a6f0f63fd493d3a064008ab3980fe4be55c3001 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 0a6f0f6 bump release for test build