these 3 derivations will be built:
  /nix/store/2kb81gwgcbkmbdwwaxg9mdmfpv6vfmfy-serde_json-1.0.151.drv
  /nix/store/fp1ik82w5fp1m7wf75zfmxs8hb2pj9r0-cargo-vendor-dir.drv
  /nix/store/2jznsxc7k9mx6myq3g1dl58mb58p2gmg-bob-0.1.0.drv