$ git clone -n https://github.com/xcp-ng-rpms/xapi.git /var/lib/mock/v9.0-u-ydi1-11602-29896/root/chroot_tmpdir/scmroot/xapi
Cloning into '/var/lib/mock/v9.0-u-ydi1-11602-29896/root/chroot_tmpdir/scmroot/xapi'...
$ git fetch origin b836b077ebbb68277cb1c0886b9a3685490f6405:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xapi
 * [new ref]         b836b077ebbb68277cb1c0886b9a3685490f6405 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b836b07 bump release for test build