```
    unvanquished-assets = runCommandNoCC "unvanquished-assets" {
      outputHash = "sha256:1x943sxbgd41dhhc4j43y8vdwj74g9rbxyz1d7an82zbjsp34lak";
      inherit version;
      buildInputs = [ aria2 ];
      meta = {
        license = lib.licenses.cc-by-sa-25;
      };
    } "aria2c http://cdn.unvanquished.net/unvanquished_$version.torrent -d $out --seed-time=0";
```

gives
```
(OK):download completed.
output path '/nix/store/50mb75967rhjp5nan8dm2lr12awhgckq-unvanquished-assets' should be a non-executable regular file
note: keeping build directory '/tmp/nix-build-unvanquished-assets.drv-13'
cannot build derivation '/nix/store/bxkdv6wn8zp06xhhiygl2r9rgqbxav46-Unvanquished.desktop.drv': 1 dependencies couldn't be built
```