anchor.diff:          # Have `configure' avoid `/usr/bin/nroff' in non-chroot builds.
           NROFF = "${groff}/bin/nroff";
   
  -        nativeBuildInputs = ops useRailsExpress [ autoreconfHook bison ];
  +        nativeBuildInputs =
  +             ops useRailsExpress [ autoreconfHook bison ]
  +          ++ ops (stdenv.buildPlatform != stdenv.hostPlatform) [
  +               buildPackages.ruby
  +             ];
           buildInputs =
                (op fiddleSupport libffi)
             ++ (ops cursesSupport [ ncurses readline ])
  
positive.code:             "--with-out-ext=tk"
              # on yosemite, "generating encdb.h" will hang for a very long time without this flag
              "--with-setjmp-type=setjmp"
            ];
  
          installFlags = stdenv.lib.optionalString docSupport "install-doc";
          # Bundler tries to create this directory
          postInstall = ''
            # Update rubygems
            pushd rubygems
            $out/bin/ruby setup.rb
            popd
  
            # Remove unnecessary groff reference from runtime closure, since it's big
  
negative.code:     isRuby25 = ver.majMin == "2.5";
      baseruby = self.override { useRailsExpress = false; };
      self = lib.makeOverridable (
    { stdenv, buildPackages, lib
        , fetchurl, fetchpatch, fetchFromSavannah, fetchFromGitHub
        , useRailsExpress ? true
        , zlib, zlibSupport ? true
        , openssl, opensslSupport ? true
  