$ git clone -n https://github.com/xcp-ng-rpms/xs-opam-repo.git /var/lib/mock/v8.3-u-asultanov2-9196-27999/root/chroot_tmpdir/scmroot/xs-opam-repo
Cloning into '/var/lib/mock/v8.3-u-asultanov2-9196-27999/root/chroot_tmpdir/scmroot/xs-opam-repo'...
$ git fetch origin cbab59fb564f4a9240b48f0e16f00c527b492f64:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xs-opam-repo
 * [new ref]         cbab59fb564f4a9240b48f0e16f00c527b492f64 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at cbab59f bump release for test build