$ git clone -n https://github.com/xcp-ng-rpms/xen.git /var/lib/mock/v9.0-u-ydi1-11193-29584/root/chroot_tmpdir/scmroot/xen
Cloning into '/var/lib/mock/v9.0-u-ydi1-11193-29584/root/chroot_tmpdir/scmroot/xen'...
$ git fetch origin 8091fcb7227005303b69c9895de8ff4e37037bd0:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xen
 * [new ref]         8091fcb7227005303b69c9895de8ff4e37037bd0 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 8091fcb bump release for test build