$ git clone -n https://src.fedoraproject.org/rpms/FlightGear-Atlas.git /var/lib/mock/f40-build-2117771-50725/root/chroot_tmpdir/scmroot/FlightGear-Atlas
Cloning into '/var/lib/mock/f40-build-2117771-50725/root/chroot_tmpdir/scmroot/FlightGear-Atlas'...
$ git fetch origin e05b04938d73cd1d5f9b48afc23c49e0ecbc31a2:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/FlightGear-Atlas
 * [new ref]         e05b04938d73cd1d5f9b48afc23c49e0ecbc31a2 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at e05b049 rebuild with newer SimGear