these 4 derivations will be built:
  /nix/store/hxqhk85gg8j95wpi2i4pi02nqqhx3l48-crate-libc-0.2.190.tar.gz.drv
  /nix/store/v9y5g4zcrs1px9mqhmlwx7ckyq20d6fv-libc-0.2.190.drv
  /nix/store/9j69fhdclwr2g9c79x78srbd5p62k0p1-cargo-vendor-dir.drv
  /nix/store/q3ddma95l22h5x7qqx9dkrz5f5zb5ykc-bob-0.1.0.drv