anchor.diff:  
     src = fetchurl {
       url = "mirror://sourceforge/scons/${name}-${version}.tar.gz";
  -    sha256 = "0qk74nrnm9qlijrq6gmy8cyhjgp0gis4zx44divnr8n487d5308a";
  +    sha256 = "4139ed14f60dd2ebcd47c59984d14705636180eb27b3d1b2949489e514b1921d";
     };
   
     buildInputs = [python makeWrapper];
  
positive.code:     homepage = "http://scons.org/";
      description = "An improved, cross-platform substitute for Make";
      license = "MIT";
      longDescription =
      '' SCons is an Open Source software construction tool. Think of
         SCons as an improved, cross-platform substitute for the classic
         Make utility with integrated functionality similar to
         autoconf/automake and compiler caches such as ccache. In short,
         SCons is an easier, more reliable and faster way to build
         software.
      '';
      platforms = stdenv.lib.platforms.all;
      maintainers = [ stdenv.lib.maintainers.simons ];
  
negative.code: 
  let
    name = "scons";
    version = "2.1.0";
  in
  
  stdenv.mkDerivation {
  