$ git clone -n https://github.com/xcp-ng-rpms/xapi.git /var/lib/mock/v8.3-u-gtn2-9014-27911/root/chroot_tmpdir/scmroot/xapi
Cloning into '/var/lib/mock/v8.3-u-gtn2-9014-27911/root/chroot_tmpdir/scmroot/xapi'...
$ git fetch origin 3afff77664c5f6c7d88469a29bc83dc27b5fe3e1:KOJI_FETCH_HEAD
From https://github.com/xcp-ng-rpms/xapi
 * [new ref]         3afff77664c5f6c7d88469a29bc83dc27b5fe3e1 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 3afff77 bump release for test build