$ git clone -n https://src.fedoraproject.org/rpms/polymake.git /var/lib/mock/f38-build-side-42-init-devel-965346-28807/root/chroot_tmpdir/scmroot/polymake
Cloning into '/var/lib/mock/f38-build-side-42-init-devel-965346-28807/root/chroot_tmpdir/scmroot/polymake'...
$ git fetch origin af9fdb6c8133f47f607ea5e448f8658e7c859640:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/polymake
 * [new ref]         af9fdb6c8133f47f607ea5e448f8658e7c859640 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at af9fdb6 Version 4.9.  Recommend plantri.