Is there a neat way of using gitIgnoreSource with haskellPackages.developPackage

At the moment this seems to be the neatest way:

```nix
haskellPackages.developPackage rec {
  root = ./.;
  modifier = drv:
    pkgs.haskell.lib.overrideSrc drv {
      src = (pkgs.nix-gitignore.gitignoreSource [ ] root);
    };
}
```

Sadly this doesn't work:

```
haskellPackages.developPackage rec {
  root = pkgs.nix-gitignore.gitignoreSource [ ] ./.;
}
```