$ git clone -n https://github.com/xcp-ng-rpms/xen.git /var/lib/mock/v9.0-u-ydi1-11377-29683/root/chroot_tmpdir/scmroot/xen
Cloning into '/var/lib/mock/v9.0-u-ydi1-11377-29683/root/chroot_tmpdir/scmroot/xen'...
$ git fetch origin f18830c4f68b2703700dc6f44c6875d412016198:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xen
 * [new ref]         f18830c4f68b2703700dc6f44c6875d412016198 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f18830c bump release for test build