$ git clone -n https://src.fedoraproject.org/rpms/polymake.git /var/lib/mock/f41-build-858155-168316/root/chroot_tmpdir/scmroot/polymake
Cloning into '/var/lib/mock/f41-build-858155-168316/root/chroot_tmpdir/scmroot/polymake'...
$ git fetch origin f2053ec948f61e2d84c780fd9066e6da40ff554e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/polymake
 * [new ref]         f2053ec948f61e2d84c780fd9066e6da40ff554e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f2053ec Version 4.13