[gnome-music] query: Minor cleanup to album songs query

[Marinus Schraal <mschraal src gnome org>]

commit e85b2cb5fb3db58531266e126529adadc9694f7c
Author: Marinus Schraal <mschraal src gnome org>
Date:   Tue Oct 25 15:49:55 2016 +0200

    query: Minor cleanup to album songs query

 gnomemusic/query.py |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/gnomemusic/query.py b/gnomemusic/query.py
index e91e4bd..d670831 100644
--- a/gnomemusic/query.py
+++ b/gnomemusic/query.py
@@ -285,8 +285,8 @@ class Query():
                 (STRSTARTS(nie:url(?song), '%(music_dir)s/')))
     }
     ORDER BY
-         nmm:setNumber(nmm:musicAlbumDisc(?song))
-         nmm:trackNumber(?song)
+         ?album_disc_number
+         ?track_number
          tracker:added(?song)
     '''.replace('\n', ' ').strip() % {
             'album_id': album_id,