these 4 derivations will be built:
  /nix/store/p8fc1kdw1dx1c0nc9ppy24ac6x2may8q-Cargo.toml.drv
  /nix/store/g5lhz84sdlz9lnpk380w0qni0pzxyl2s-source.drv
  /nix/store/5pqi6bnm9w8x212rblj6z01lsgmd65a4-harmonia-deps-3.3.0.drv
  /nix/store/pcmirs7il6i423yas3k9pff3dn77rnqm-harmonia-llvm-cov-3.3.0.drv