$ git clone -n https://src.fedoraproject.org/rpms/polymake.git /var/lib/mock/f41-build-1023935-18170/root/chroot_tmpdir/scmroot/polymake
Cloning into '/var/lib/mock/f41-build-1023935-18170/root/chroot_tmpdir/scmroot/polymake'...
$ git fetch origin 3848745a79a020413b88f710e2696d8ed5c0a6b0:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/polymake
 * [new ref]         3848745a79a020413b88f710e2696d8ed5c0a6b0 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 3848745 Update configure for Perl 5.40