$ git clone -n https://src.fedoraproject.org/rpms/FlightGear.git /var/lib/mock/f40-build-2236861-53523/root/chroot_tmpdir/scmroot/FlightGear
Cloning into '/var/lib/mock/f40-build-2236861-53523/root/chroot_tmpdir/scmroot/FlightGear'...
$ git fetch origin 7e9dff0efbbfde72073a0a68da5b2abfc1757dd5:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/FlightGear
 * [new ref]         7e9dff0efbbfde72073a0a68da5b2abfc1757dd5 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 7e9dff0 new upstream release