$ git clone -n https://github.com/xcp-ng-rpms/xapi.git /var/lib/mock/v8.3-incoming-11459-29755/root/chroot_tmpdir/scmroot/xapi
Cloning into '/var/lib/mock/v8.3-incoming-11459-29755/root/chroot_tmpdir/scmroot/xapi'...
$ git fetch origin 69bd37ce20a094fcd55dc0093d3bd555a1226829:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xapi
 * [new ref]         69bd37ce20a094fcd55dc0093d3bd555a1226829 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 69bd37c Proper fix for export of QCOW2-backed VDIs with snapshots