these 4 derivations will be built:
  /nix/store/ycp1lj8bck2lq7ph6cajrqmf3v9l0i1h-Cargo.toml.drv
  /nix/store/xp2994yg5a00kb98091xl3f10hfhngcn-source.drv
  /nix/store/9k60l951irmcj98f6ip0i916ddddiqj6-harmonia-deps-3.2.0.drv
  /nix/store/n2sqkrj0qbaml9c1diqvm7d2sm02vr4g-harmonia-3.2.0.drv