these 4 derivations will be built:
  /nix/store/wpcs0v4cb2ak6di1nxipbdd6qw8cwpmj-Cargo.toml.drv
  /nix/store/7df37yqaaqnynr3jz0yqacriba1xcnj7-source.drv
  /nix/store/a74kx1klhf2sfh1g5fl46zmwxf7ln2b3-harmonia-deps-3.1.0.drv
  /nix/store/dbdmw4p7yd3jm4ldp6zz3rjhixazq4zj-harmonia-3.1.0.drv