these 4 derivations will be built:
  /nix/store/kg8n5v96w9dqhc4bh5p24zfhwwj4hx6d-Cargo.toml.drv
  /nix/store/r95hhg7953hiz9c2mcl9v5i5jbkp8zkf-source.drv
  /nix/store/5dbrm8dh22d0yirf426l0cwfjdj4qfnr-harmonia-deps-3.2.0.drv
  /nix/store/k129asjfpzd7p1lbvzcl9qf9zxyxfzfd-harmonia-llvm-cov-3.2.0.drv