$ git clone -n https://src.fedoraproject.org/rpms/R-Rmpfr.git /var/lib/mock/f38-build-side-42-init-devel-736476-27646/root/chroot_tmpdir/scmroot/R-Rmpfr
Cloning into '/var/lib/mock/f38-build-side-42-init-devel-736476-27646/root/chroot_tmpdir/scmroot/R-Rmpfr'...
$ git fetch origin 64e27eec33d17373e00979c7f8ae309177aa2167:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-Rmpfr
 * [new ref]         64e27eec33d17373e00979c7f8ae309177aa2167 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 64e27ee Rebuilt for https://fedoraproject.org/wiki/Fedora_38_Mass_Rebuild