these 2 derivations will be built:
  /nix/store/vvr8rb2j64lrjgk1l846glws3l5p99wx-freebuff-0.2.33.drv
  /nix/store/yk9nrxgp5bz7fllrvda60rvjww3j1brb-check-freebuff.drv