$ git clone -n https://src.fedoraproject.org/rpms/polymake.git /var/lib/mock/f40-build-2670976-67370/root/chroot_tmpdir/scmroot/polymake
Cloning into '/var/lib/mock/f40-build-2670976-67370/root/chroot_tmpdir/scmroot/polymake'...
$ git fetch origin 8363ec1cd0bb223d4bdc53dbc800f57d29bb94ab:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/polymake
 * [new ref]         8363ec1cd0bb223d4bdc53dbc800f57d29bb94ab -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 8363ec1 Rebuild for cocoalib 0.99850