these 2 derivations will be built:
  /nix/store/y01yyld9xfpf7q5a5q4gg8si44z290cw-iets-0.1.0.drv
  /nix/store/2yysi1crr2az4chdwvm0qmnknil6w67d-iets-diff-e2e.drv