anchor.diff:    };
   
     netifaces = buildPythonPackage rec {
  -    version = "0.8";
  +    version = "0.10.4";
       name = "netifaces-${version}";
   
       src = fetchurl {
  -      url = "http://alastairs-place.net/projects/netifaces/${name}.tar.gz";
  -      sha256 = "1v5i39kx4yz1pwgjfbzi63w55l2z318zgmi9f77ybmmkil1i39sk";
  +      url = "http://pypi.python.org/packages/source/n/netifaces/${name}.tar.gz";
  +      sha256 = "1plw237a4zib4z8s62g0mrs8gm3kjfrp5sxh6bbk9nl3rdls2mln";
       };
   
       meta = {
  
positive.code:     name = "zope.security-4.0.1";
  
      src = fetchurl {
        url = "http://pypi.python.org/packages/source/z/zope.security/zope.security-3.7.4.tar.gz";
        md5 = "072ab8d11adc083eace11262da08630c";
      };
  
      propagatedBuildInputs = [
        zope_component zope_configuration zope_i18nmessageid zope_schema
        zope_proxy
      ];
  
      meta = {
  
negative.code: 
    dulwich = buildPythonPackage rec {
      name = "dulwich-0.8.7";
      disabled = isPy3k || isPyPy;
  
      src = fetchurl {
        url = "http://samba.org/~jelmer/dulwich/${name}.tar.gz";
  