Vispy usage with redundant fontconfig

analysis.nix

with import <nixpkgs> {};

stdenv.mkDerivation rec {
  name = "data-analysis";

  LD_LIBRARY_PATH = "${pkgs.fontconfig.lib}/lib";

  buildInputs = [
    (pkgs.python27.withPackages (packages: with packages; [
      h5py
      numpy
      (import ./vispy.nix)
    ]))
    pkgs.fontconfig
  ];
}

vispy.nix

with import <nixpkgs> {};
with pkgs.python27Packages;

buildPythonPackage rec {
  name = "vispy-master";

  src = pkgs.fetchgit {
    url = "https://github.com/vispy/vispy";
    sha256 = "1zm0gglvzlhliicwv5rm9nv34f1ql2i5vns8ybqr78r4bcz0f6dp";
    rev = "38001b70d54a5519eb296d44a196c081fcbd7fad";
  };

  LD_LIBRARY_PATH = "${pkgs.fontconfig.lib}/lib";

  buildInputs = [ pkgs.fontconfig ];
  propagatedBuildInputs = [ numpy ];

  meta = {
    homepage = "http://vispy.org/";
    description = "Interactive scientific data visualization";
    license = licenses.bsd3;
    maintainers = [];
  };
}