$ git clone -n https://github.com/xcp-ng-rpms/xs-opam-repo /var/lib/mock/v9.0-u-ydi1-11229-29599/root/chroot_tmpdir/scmroot/xs-opam-repo
Cloning into '/var/lib/mock/v9.0-u-ydi1-11229-29599/root/chroot_tmpdir/scmroot/xs-opam-repo'...
$ git fetch origin 5b080198986a72b350c648903ceb4907e61fbb31:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xs-opam-repo
 * [new ref]         5b080198986a72b350c648903ceb4907e61fbb31 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 5b08019 bump release for test build