$ git clone -n https://src.fedoraproject.org/rpms/polymake.git /var/lib/mock/f39-build-1679856-41015/root/chroot_tmpdir/scmroot/polymake
Cloning into '/var/lib/mock/f39-build-1679856-41015/root/chroot_tmpdir/scmroot/polymake'...
$ git fetch origin 152e5b20daf7116e8c67a716eacc05c7770e4e5e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/polymake
 * [new ref]         152e5b20daf7116e8c67a716eacc05c7770e4e5e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 152e5b2 Version 4.11