$ git clone -n https://src.fedoraproject.org/rpms/fbg2.git /var/lib/mock/f45-build-8718-394/root/chroot_tmpdir/scmroot/fbg2
Cloning into '/var/lib/mock/f45-build-8718-394/root/chroot_tmpdir/scmroot/fbg2'...
$ git fetch origin 9093ad6af618d9241497fdf5d2e23f5d792884a5:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/fbg2
 * [new ref]         9093ad6af618d9241497fdf5d2e23f5d792884a5 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 9093ad6 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild