these 4 derivations will be built:
  /nix/store/kx87avanh3vrkqiqi8v2015kdd7hrn1c-Cargo.toml.drv
  /nix/store/lgq704nc28p1cgximdwhfp942b1jg78h-source.drv
  /nix/store/5vll9qn57ninwcwh5rcx8rhahyr43l8k-harmonia-deps-3.3.0.drv
  /nix/store/5cg2zn34j4ivw1nlhv1a4arkwmas4bkx-harmonia-llvm-cov-3.3.0.drv