$ git clone -n https://src.fedoraproject.org/rpms/polymake.git /var/lib/mock/f42-build-3486950-45831/root/chroot_tmpdir/scmroot/polymake
Cloning into '/var/lib/mock/f42-build-3486950-45831/root/chroot_tmpdir/scmroot/polymake'...
$ git fetch origin 21f10ab1dc819bb911b2f06c90d6a4e28e497e43:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/polymake
 * [new ref]         21f10ab1dc819bb911b2f06c90d6a4e28e497e43 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 21f10ab Rebuild for flint 3.2.1