Revert "Merge pull request #3718 from MP2E/lens_4_4_update"

This reverts commit 53fab4004e171a3490842c921abd8551a73278b1, reversing
changes made to 08e4d586009768e0f2a874125ac618424703b7f5.
Build a few NixOS system closures on Hydra

This will allow us to keep track of the evolution of closure sizes of
some typical configurations. (Hydra stores closure sizes in its
database.)
Fix various evaluation problems

http://hydra.nixos.org/build/13616685