anchor.diff:  
   buildPythonPackage rec {
     name = "matplotlib-${version}";
  -  version = "1.5.0";
  +  version = "1.5.1";
   
     src = fetchurl {
       url = "https://pypi.python.org/packages/source/m/matplotlib/${name}.tar.gz";
  -    sha256 = "67b08b1650a00a6317d94b76a30a47320087e5244920604c5462188cba0c2646";
  +    sha256 = "3ab8d968eac602145642d0db63dd8d67c85e9a5444ce0e2ecb2a8fedc7224d40";
     };
   
     NIX_CFLAGS_COMPILE = stdenv.lib.optionalString stdenv.isDarwin "-I${libcxx}/include/c++/v1";
  
positive.code:     maintainers = with maintainers; [ lovek323 ];
      platforms   = platforms.unix;
    };
  }
  
negative.code: 
    patches = stdenv.lib.optionals stdenv.isDarwin [ ./darwin-stdenv.patch ];
  
    checkPhase = ''
      ${python.interpreter} tests.py
    '';
  
    # The entry point for running tests, tests.py, is not included in the release.
    # https://github.com/matplotlib/matplotlib/issues/6017
    doCheck = false;
  
    prePatch = ''
      # Failing test: ERROR: matplotlib.tests.test_style.test_use_url
      sed -i 's/test_use_url/fails/' lib/matplotlib/tests/test_style.py
  