these 4 derivations will be built:
  /nix/store/x2a6m8afnjb02rk9gmf83q7qyacrr4c5-Cargo.toml.drv
  /nix/store/089rdz6r89l92rixdxw4lka5q1pra00p-source.drv
  /nix/store/m1dygm9n5zay84mx46rxskjq1m1an5pz-harmonia-deps-3.2.0.drv
  /nix/store/59m9scz4027h0s8d3193sdfypdc121q3-harmonia-llvm-cov-3.2.0.drv