$ git clone -n https://src.fedoraproject.org/rpms/polymake.git /var/lib/mock/f43-perl-60963095-6586821/root/chroot_tmpdir/scmroot/polymake
Cloning into '/var/lib/mock/f43-perl-60963095-6586821/root/chroot_tmpdir/scmroot/polymake'...
$ git fetch origin 1c55831bf85c640b75d1a8a8b0698cb23c0627f4:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/polymake
 * [new ref]         1c55831bf85c640b75d1a8a8b0698cb23c0627f4 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 1c55831 Adapt for Perl 5.42.0 update