anchor.diff:  
     preFixup = ''
       # 'hide' the template file from shebang-patching
  -    chmod -x $out/opt/vagrant/embedded/gems/gems/bundler-1.10.6/lib/bundler/templates/Executable
  +    chmod -x $out/opt/vagrant/embedded/gems/gems/bundler-1.12.5/lib/bundler/templates/Executable
       chmod -x $out/opt/vagrant/embedded/gems/gems/vagrant-${version}/plugins/provisioners/salt/bootstrap-salt.sh
     '';
   
     postFixup = ''
  -    chmod +x $out/opt/vagrant/embedded/gems/gems/bundler-1.10.6/lib/bundler/templates/Executable
  +    chmod +x $out/opt/vagrant/embedded/gems/gems/bundler-1.12.5/lib/bundler/templates/Executable
       chmod +x $out/opt/vagrant/embedded/gems/gems/vagrant-${version}/plugins/provisioners/salt/bootstrap-salt.sh
     '';
   }
  
positive.code: assert stdenv.system == "x86_64-linux" || stdenv.system == "i686-linux";
  
  let
    version = "1.8.1";
    rake = buildRubyGem {
      inherit ruby;
      gemName = "rake";
  
negative.code:     if stdenv.system == "x86_64-linux" then
        fetchurl {
          url    = "https://releases.hashicorp.com/vagrant/${version}/vagrant_${version}_x86_64.deb";
          sha256 = "fd38d8e00e494a617201facb42fc2cac627e5021db15e91c2a041eac6a2d8208";
        }
      else
        fetchurl {
          url    = "https://releases.hashicorp.com/vagrant/${version}/vagrant_${version}_i686.deb";
          sha256 = "555351717cacaa8660821df8988cc40a39923b06b698fca6bb90621008aab06f";
        };
  
    meta = with stdenv.lib; {
  