these 4 derivations will be built:
  /nix/store/11i6868wzj71hrr575pd1jmbxy65sgw7-Cargo.toml.drv
  /nix/store/dyyg330af0h82z0bw8f9jrki328yfhl2-source.drv
  /nix/store/lzj6zsz9prvc6037kyicvfx94c82df4j-harmonia-deps-3.2.0.drv
  /nix/store/yp06sq4k1b1qbwaamsxpbqdysq9b49b8-harmonia-llvm-cov-3.2.0.drv