anchor.diff:  { stdenv, fetchurl, fetchpatch, dpkg, curl, libarchive, openssl, ruby, buildRubyGem, libiconv
  -, libxml2, libxslt, makeWrapper, p7zip, xar, gzip, cpio }:
  +, libxml2, libxslt, libffi, makeWrapper, p7zip, xar, gzip, cpio }:
   
   let
     version = "1.9.5";
  
positive.code:     ln -s ${ruby}/bin/ruby opt/vagrant/embedded/bin
  
      # ruby libs
      rm -rf opt/vagrant/embedded/lib
      ln -s ${ruby}/lib opt/vagrant/embedded/lib
  
      # libiconv: iconv
      rm opt/vagrant/embedded/bin/iconv
  
negative.code:     rm opt/vagrant/embedded/bin/{xslt-config,xsltproc}
      ln -s ${libxslt.dev}/bin/xslt-config opt/vagrant/embedded/bin
      ln -s ${libxslt.bin}/bin/xsltproc opt/vagrant/embedded/bin
  
      # libffi
      ln -s ${libffi}/lib/libffi.so.6 opt/vagrant/embedded/lib/libffi.so.6
  
      mkdir -p "$out"
      cp -r opt "$out"
  