$ git clone -n https://github.com/xcp-ng-rpms/xapi.git /var/lib/mock/v8.3-u-psafont2-9715-28427/root/chroot_tmpdir/scmroot/xapi
Cloning into '/var/lib/mock/v8.3-u-psafont2-9715-28427/root/chroot_tmpdir/scmroot/xapi'...
$ git fetch origin 6912b05eb095d2c24671bcbff7c174afff4319eb:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xapi
 * [new ref]         6912b05eb095d2c24671bcbff7c174afff4319eb -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 6912b05 bump release for test build