Remove top-level dbus_python and pythonDBus.

See #11567.

Furthermore, it renames pythonPackages.dbus to pythonPackages.dbus-
python as that's the name upstream uses.

There is a small rebuild but I couldn't figure out the actual cause.

pkgs/os-specific/linux/bluez/default.nix

@@ -1,14 +1,13 @@
-{ stdenv, fetchurl, pkgconfig, dbus, glib, libusb, alsaLib, python, makeWrapper
-, pythonDBus, pygobject, readline, libsndfile }:
+{ stdenv, fetchurl, pkgconfig, dbus, glib, libusb, alsaLib, pythonPackages, makeWrapper
+, readline, libsndfile }:
 
 assert stdenv.isLinux;
 
 let
-  pythonpath = "${pythonDBus}/lib/${python.libPrefix}/site-packages:"
-    + "${pygobject}/lib/${python.libPrefix}/site-packages";
-in
-   
-stdenv.mkDerivation rec {
+  inherit (pythonPackages) python;
+  pythonpath = "${pythonPackages.dbus}/lib/${python.libPrefix}/site-packages:"
+    + "${pythonPackages.pygobject}/lib/${python.libPrefix}/site-packages";
+in stdenv.mkDerivation rec {
   name = "bluez-4.101";
    
   src = fetchurl {