$ git clone -n https://src.fedoraproject.org/rpms/FlightGear.git /var/lib/mock/f42-build-3364886-45045/root/chroot_tmpdir/scmroot/FlightGear
Cloning into '/var/lib/mock/f42-build-3364886-45045/root/chroot_tmpdir/scmroot/FlightGear'...
$ git fetch origin 9d10bf68263e6dc2dd55ae490f2cf9a9c839cda4:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/FlightGear
 * [new ref]         9d10bf68263e6dc2dd55ae490f2cf9a9c839cda4 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 9d10bf6 new upstream release