anchor.diff:  
       propagatedBuildInputs = with self; [
         twitter-common-collections setproctitle setuptools six ansicolors
  -      packaging pathspec scandir twitter-common-dirutil psutil requests2
  +      packaging pathspec_0_5 scandir twitter-common-dirutil psutil requests2
         pystache pex docutils markdown pygments twitter-common-confluence
         fasteners coverage pywatchman futures cffi
       ];
  
positive.code:     };
    };
  
    pathspec = buildPythonPackage rec {
      pname   = "pathspec";
      version = "0.3.4";
  
negative.code:     src = self.fetchPypi {
        inherit pname version;
        sha256 = "0a37yrr2jhlg8aiynxivh2xqani7l9j725qxzrm7cm7m4rfcl1bn";
      };
  
      meta = {
        description = "Utility library for gitignore-style pattern matching of file paths";
        homepage = "https://github.com/cpburnz/python-path-specification";
        license = licenses.mpl20;
        maintainers = with maintainers; [ copumpkin ];
      };
    };
  
    pathspec_0_5 = buildPythonPackage rec {
      pname   = "pathspec";
      version = "0.5.0";
      name    = "${pname}-${version}";
  
      src = self.fetchPypi {
        inherit pname version;
        sha256 = "07yx1gxj9v1iyyiy5fhq2wsmh4qfbrx158wi7jb0nx6lah80ffma";
      };
  
      meta = {
  