xpra: Add python notify module.

This is not needed to run XPRA, but gets rid of a few nasty errors.

XPRA is using the notify library to display nice desktop notifications, so there
might be users who actually like to have those funny things.

pkgs/tools/X11/xpra/default.nix

@@ -1,5 +1,5 @@
 { stdenv, fetchurl, pkgconfig, python, cython
-, pygtk, pygobject, pycairo, xlibs, gtk
+, pygtk, pygobject, pycairo, notify, xlibs, gtk
 , ffmpeg, x264, libvpx, makeWrapper}:
 
 stdenv.mkDerivation rec {

pkgs/top-level/all-packages.nix

@@ -7683,7 +7683,9 @@ let
   libxpdf = callPackage ../applications/misc/xpdf/libxpdf.nix {
   };
 
-  xpra = callPackage ../tools/X11/xpra { };
+  xpra = callPackage ../tools/X11/xpra {
+    inherit (pythonPackages) notify;
+  };
 
   xscreensaver = callPackage ../misc/screensavers/xscreensaver {
     inherit (gnome) libglade;