$ git clone -n https://src.fedoraproject.org/rpms/R-systemfonts.git /var/lib/mock/f45-build-6443-348/root/chroot_tmpdir/scmroot/R-systemfonts
Cloning into '/var/lib/mock/f45-build-6443-348/root/chroot_tmpdir/scmroot/R-systemfonts'...
$ git fetch origin 743a202abc574f8b4290e7fa1523bd74433c84fa:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-systemfonts
 * [new ref]         743a202abc574f8b4290e7fa1523bd74433c84fa -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 743a202 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild