$ git clone -n https://github.com/xcp-ng-rpms/xen.git /var/lib/mock/v9.0-u-ydi1-11542-29858/root/chroot_tmpdir/scmroot/xen
Cloning into '/var/lib/mock/v9.0-u-ydi1-11542-29858/root/chroot_tmpdir/scmroot/xen'...
$ git fetch origin 75ae8190856b97156abf63c8726c02850c6f2eef:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xen
 * [new ref]         75ae8190856b97156abf63c8726c02850c6f2eef -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 75ae819 bump release for test build