these 2 derivations will be built:
  /nix/store/aaw28z4y8k9n3nqb0dax4y46yb12g8jz-iets-0.1.0.drv
  /nix/store/xdycdj3vaas7h6vadm44gfa8dkk05sw4-iets-diff-e2e.drv