these 2 derivations will be built:
  /nix/store/vswaxg1wv3jsqcv1hfi3zn8fx8s2m24q-cargo-vendor-dir.drv
  /nix/store/9jh6b5s44lagp1jsq9m41y477iwk3gjm-nixfmt-rs-0.5.3.drv