$ git clone -n https://src.fedoraproject.org/rpms/R-later.git /var/lib/mock/f45-build-6207-347/root/chroot_tmpdir/scmroot/R-later
Cloning into '/var/lib/mock/f45-build-6207-347/root/chroot_tmpdir/scmroot/R-later'...
$ git fetch origin b951a7e6c475a2d6a3845a11d5c27abb44f9fe5b:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-later
 * [new ref]         b951a7e6c475a2d6a3845a11d5c27abb44f9fe5b -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b951a7e Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild