xpra: Don't include cython into store requisites.

Cython is not required in order to run XPRA, so we now explicitly specify what
should be put into PYTHONPATH instead of using the PYTHONPATH which is set
during build time.

That way we don't get unnecessary stuff in /nix/store, like the mentioned
cython compiler/interpreter.

pkgs/tools/X11/xpra/default.nix

@@ -1,6 +1,8 @@
-{stdenv, fetchurl, pkgconfig, python, cython, pygtk, xlibs, gtk, ffmpeg, x264, libvpx, makeWrapper}:
+{ stdenv, fetchurl, pkgconfig, python, cython
+, pygtk, pygobject, pycairo, xlibs, gtk
+, ffmpeg, x264, libvpx, makeWrapper}:
 
-stdenv.mkDerivation {
+stdenv.mkDerivation rec {
   name = "xpra-0.3.2";
   
   src = fetchurl {
@@ -8,8 +10,10 @@ stdenv.mkDerivation {
     sha256 = "1s1z6r0r78qvf59ci3vxammjz7lj5m64jyk0bfn7yxd5jl3sy41y";
   };
 
+  buildNativeInputs = [ cython ];
+
   buildInputs = [
-    pkgconfig python cython pygtk gtk ffmpeg x264 libvpx makeWrapper
+    pkgconfig python pygtk gtk ffmpeg x264 libvpx makeWrapper
     xlibs.inputproto xlibs.libXcomposite xlibs.libXdamage xlibs.libXtst
   ];
 
@@ -19,13 +23,20 @@ stdenv.mkDerivation {
     ./do-build
   '';
 
+  pythonPaths = [
+    "$out/lib/python"
+    "$(toPythonPath ${pygtk})/gtk-2.0"
+  ] ++ map (i: "$(toPythonPath ${i})") [
+    pygobject pycairo notify
+  ];
+
   installPhase = ''
     mkdir -p $out
     cp -r install/* $out
 
     for i in $(cd $out/bin && ls); do
         wrapProgram $out/bin/$i \
-            --set PYTHONPATH "$out/lib/python:$(toPythonPath ${pygtk})/gtk-2.0:$PYTHONPATH" \
+            --set PYTHONPATH "${stdenv.lib.concatStringsSep ":" pythonPaths}" \
             --prefix PATH : "${xlibs.xauth}/bin:${xlibs.xorgserver}/bin:${xlibs.xmodmap}/bin"
     done
   '';