these 4 derivations will be built:
  /nix/store/0rgsfj3d304aay1wc7jbd359rgay18z6-Cargo.toml.drv
  /nix/store/y8dmjw3rx8mw2mrm4rzl1p5y8vbnayb0-source.drv
  /nix/store/9kl89yh5zr2swncghjgnka1ghs54ccv8-flakelet-relay-deps-0.1.0.drv
  /nix/store/4fkxcgsxwjsf3jlj398vhmvw9qdfkd6d-flakelet-relay-0.1.0.drv