anchor.diff:  stdenv.mkDerivation {
     pname = "zsh";
     inherit version;
  +  outputs = [ "out" "doc" "info" "man" ];
   
     src = fetchurl {
       url = "mirror://sourceforge/zsh/zsh-${version}.tar.xz";
  
positive.code:     mv $out/etc/zprofile $out/etc/zprofile_zwc_is_used
  
      rm $out/bin/zsh-${version}
    '';
    # XXX: patch zsh to take zwc if newer _or equal_
  
  
negative.code:   checkFlags = map (T: "TESTNUM=${T}") (lib.stringToCharacters "ABCDEVW");
  
    # XXX: think/discuss about this, also with respect to nixos vs nix-on-X
    postInstall = ''
      make install.info install.html
      mkdir -p $out/etc/
      cat > $out/etc/zprofile <<EOF
  if test -e /etc/NIXOS; then
  