$ git clone -n https://github.com/xcp-ng-rpms/xapi /var/lib/mock/v8.3-u-psafont1-10516-29072/root/chroot_tmpdir/scmroot/xapi
Cloning into '/var/lib/mock/v8.3-u-psafont1-10516-29072/root/chroot_tmpdir/scmroot/xapi'...
$ git fetch origin c66dd282b96c714dd5878e97f4e76f75c9e27f23:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xapi
 * [new ref]         c66dd282b96c714dd5878e97f4e76f75c9e27f23 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at c66dd28 bump release for test build