anchor.diff:  
     XDG_RUNTIME_DIR = "/tmp";
   
  -  nativeBuildInputs = [ pkg-config ];
  +  nativeBuildInputs = [
  +    pkg-config
  +    setuptools-scm
  +    setuptools-scm-git-archive
  +  ];
   
     buildInputs = [ which sphinx ]
       ++ lib.optional enableGhostscript ghostscript
       ++ lib.optional stdenv.isDarwin [ Cocoa ];
   
     propagatedBuildInputs =
  -    [ cycler python-dateutil numpy pyparsing tornado freetype qhull
  +    [ cycler fonttools python-dateutil numpy pyparsing tornado freetype qhull
         kiwisolver certifi libpng mock pytz pillow ]
       ++ lib.optionals enableGtk3 [ cairo pycairo gtk3 gobject-introspection pygobject3 ]
       ++ lib.optionals enableTk [ tcl tk tkinter libX11 ]
  
positive.code: { lib, stdenv, fetchPypi, writeText, buildPythonPackage, isPy3k, pycairo
  , which, cycler, python-dateutil, numpy, pyparsing, sphinx, tornado, kiwisolver
  , freetype, qhull, libpng, pkg-config, mock, pytz, pygobject3, gobject-introspection
  , certifi, pillow
  , enableGhostscript ? true, ghostscript, gtk3
  , enableGtk3 ? false, cairo
  # darwin has its own "MacOSX" backend
  
negative.code:       substituteInPlace src/_c_internal_utils.c \
          --replace libX11.so.6 ${libX11}/lib/libX11.so.6 \
          --replace libwayland-client.so.0 ${wayland}/lib/libwayland-client.so.0
      '' + ''
        # avoid matplotlib trying to download dependencies
        echo "[libs]
        system_freetype=true
        system_qhull=true" > mplsetup.cfg
        cat mplsetup.cfg
        echo FFFFFFFFFFFFFFFFFFFFFFFFFFFFF
      '';
  
    # Matplotlib needs to be built against a specific version of freetype in
  