anchor.diff:    numba = buildPythonPackage rec {
       version = "0.21.0";
       name = "numba-${version}";
  -    
  +
       src = pkgs.fetchurl {
         url = "https://pypi.python.org/packages/source/n/numba/${name}.tar.gz";
         sha256 = "1806d2f6ad49ad891e9ac6fed0cc0b0489cbfcd9ba2dc81081c1c30091e77604";
       };
  -    
  +
       propagatedBuildInputs = with self; [numpy llvmlite argparse] ++ optional (!isPy3k) funcsigs ++ optional (isPy27 || isPy33) singledispatch;
       # Future work: add Cuda support.
       #propagatedBuildInputs = with self; [numpy llvmlite argparse pkgs.cudatoolkit6];
  
positive.code: 
      # there ain't none
      doCheck = false;
      
      meta = {
        description = "Mercurial extension for selecting graphically which files/hunk/lines to commit";
        homepage = https://bitbucket.org/edgimar/crecord;
  
negative.code:     checkPhase = ''
        ${self.python.executable} runtests.py
      '';
  
      meta = {
        description = "A lightweight LLVM python binding for writing JIT compilers";
        homepage = "http://llvmlite.pydata.org/";
  