anchor.diff:  
   with stdenv.lib;
   
  -let version = "3.4.2";
  +let version = "3.4.10";
       system-libraries = [
         "pcre"
         #"asio" -- XXX use package?
  
positive.code: 
    src = fetchurl {
      url = "https://fastdl.mongodb.org/src/mongodb-src-r${version}.tar.gz";
      sha256 = "0n8vspccrpd2z9xk3yjpz4gprd730dfacw914ksjzz9iadn0zdi9";
    };
  
    nativeBuildInputs = [ scons ];
  
negative.code:         url = https://projects.archlinux.org/svntogit/community.git/plain/trunk/boost160.patch?h=packages/mongodb;
          name = "boost160.patch";
          sha256 = "0bvsf3499zj55pzamwjmsssr6x63w434944w76273fr5rxwzcmh8";
        })
      ];
  
  