$ git clone -n https://src.fedoraproject.org/rpms/R-modelr.git /var/lib/mock/f45-build-6267-347/root/chroot_tmpdir/scmroot/R-modelr
Cloning into '/var/lib/mock/f45-build-6267-347/root/chroot_tmpdir/scmroot/R-modelr'...
$ git fetch origin 24b8e1d5b154a0cfe0e75b98f4ff822fb99985d3:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-modelr
 * [new ref]         24b8e1d5b154a0cfe0e75b98f4ff822fb99985d3 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 24b8e1d Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild