anchor.diff:    konfig = buildPythonPackage rec {
       name = "konfig-${version}";
       version = "0.9";
  +
  +    # konfig unconditionaly depend on configparser, even if it is part of
  +    # the standard library in python 3.2 or above.
  +    disabled = isPy3k;
  +
       src = pkgs.fetchgit {
         url = https://github.com/mozilla-services/konfig.git;
         rev = "refs/tags/${version}";
  
positive.code:     };
    };
  
    configparser = buildPythonPackage rec {
      name = "configparser-${version}";
      version = "3.3.0r2";
  
  
negative.code:   pybrowserid = buildPythonPackage rec {
      name = "PyBrowserID-${version}";
      version = "0.9.2";
      disabled = isPy3k; # Errors in the test suite.
  
      src = pkgs.fetchgit {
        url = https://github.com/mozilla/PyBrowserID.git;
        rev = "refs/tags/${version}";
  