anchor.diff:    buildInputs =
       [ pkgconfig expat x11 libdrm xlibs.makedepend xlibs.glproto
         xlibs.libXxf86vm xlibs.libXfixes xlibs.libXdamage xlibs.dri2proto
  -      lipo talloc file pythonFull flex bison
  +      lipo file python libxml2Python flex bison
       ];
   
     enableParallelBuilding = true;
  
positive.code: { stdenv, fetchurl, flex, bison, pkgconfig, x11, xlibs, libdrm, file, expat
  , pythonFull, lipo ? null, talloc }:
  
  if ! stdenv.lib.lists.elem stdenv.system stdenv.lib.platforms.mesaPlatforms then
    throw "unsupported platform for Mesa"
  
negative.code:   patches = [ ./swrast-settexbuffer.patch ];
  
    postPatch = ''
      find . -name "*.py" -exec sed -i -e "s|#! */usr/bin/env python|#! ${python}/bin/python|" {} +
    '';
  
    configureFlags =
  