anchor.diff:  
     preFixup = ''
       # 'hide' the template file from shebang-patching
  -    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 "$out/opt/vagrant/embedded/gems/gems/bundler-1.12.5/lib/bundler/templates/Executable"
       chmod +x "$out/opt/vagrant/embedded/gems/gems/vagrant-$version/plugins/provisioners/salt/bootstrap-salt.sh"
     '' +
     (stdenv.lib.optionalString stdenv.isDarwin ''
  
positive.code:       else "system ${stdenv.system} not supported";
  
    sha256 = {
      "x86_64-linux"  = "10c77b643b73dd3ad7a45a89d8ab95b58b79dc10e0cf6e760fe24abc436b2fdb";
      "i686-linux"    = "9d2a70f34ab65d8d2cb013917f221835432aa63cd4ef781c9fd1404cfcfe7898";
      "x86_64-darwin" = "14d68f599a620cf421838ed037f0a1c4467e1b67475deeff62330a21fda4937b";
    }."${stdenv.system}" or (throw "system ${stdenv.system} not supported");
  
    arch = builtins.replaceStrings ["-linux"] [""] stdenv.system;
  
negative.code: , libxml2, libxslt, makeWrapper, p7zip, xar, gzip, cpio }:
  
  let
    version = "1.9.1";
    rake = buildRubyGem {
      inherit ruby;
      gemName = "rake";
  