these 4 derivations will be built:
  /nix/store/31lzf1gm59k7wfgi6ygfay72airwlajk-Cargo.toml.drv
  /nix/store/nzgx7670v0ghbb0wk18ly8k59jn9041d-source.drv
  /nix/store/n7j3frj9gshpmvlhxaqj8sg3llyvhi6d-harmonia-deps-3.1.0.drv
  /nix/store/9lixs75zha7m3c0dvs38j8m8f9ivg7i9-harmonia-llvm-cov-3.1.0.drv