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