[Nix-dev] not only alsoInstall, we might need "mkDeriation = { options" as well

[Marc Weber]

>         alsoInstall = [ ghc ];
adding would solve some trouble for ghc and packages
adding
mkDerivation = {
  options = <some format telling the imaginary nix-env frontend which
options to put into .nixpkgs/config.nix>;
}

could tell you straight forward that you can isntall git with svn
support..

Marc Weber