This line seems to wrap a buildPackages.python script with non-buildPackages bash
```
install -D $src $out/bin/cargo-vendor-normalise
```
https://github.com/NixOS/nixpkgs/blob/909a4ba5fe89fe865f8321ba6cfb5a4350e6ea59/pkgs/build-support/rust/fetchCargoTarball.nix#L7