$ git clone -n https://src.fedoraproject.org/rpms/R-gdtools.git /var/lib/mock/f38-build-724992-99532/root/chroot_tmpdir/scmroot/R-gdtools
Cloning into '/var/lib/mock/f38-build-724992-99532/root/chroot_tmpdir/scmroot/R-gdtools'...
$ git fetch origin 4751e051c100ad85c27f4d1098184c1f359f1874:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-gdtools
 * [new ref]         4751e051c100ad85c27f4d1098184c1f359f1874 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 4751e05 R-maint-sig mass rebuild