$ git clone -n https://src.fedoraproject.org/rpms/polymake.git /var/lib/mock/f40-build-2051188-49045/root/chroot_tmpdir/scmroot/polymake
Cloning into '/var/lib/mock/f40-build-2051188-49045/root/chroot_tmpdir/scmroot/polymake'...
$ git fetch origin 66b09aa375bd6ce0fcc76c0f6ee67feae93e5f21:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/polymake
 * [new ref]         66b09aa375bd6ce0fcc76c0f6ee67feae93e5f21 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 66b09aa Rebuild for Perl 5.38.2