$ git clone -n https://github.com/xcp-ng-rpms/xen.git /var/lib/mock/v9.0-u-ydi1-11092-29520/root/chroot_tmpdir/scmroot/xen
Cloning into '/var/lib/mock/v9.0-u-ydi1-11092-29520/root/chroot_tmpdir/scmroot/xen'...
$ git fetch origin 12e92891c73be901e06eac8d7b22b9b2f3b51d70:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xen
 * [new ref]         12e92891c73be901e06eac8d7b22b9b2f3b51d70 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 12e9289 bump release for test build