[gnome-music/gnome-3-10] searchbar: don't crash if track doesn't have artist/album set

[Vadim Rutkovsky <vrutkovsky src gnome org>]

commit 3661dbf184cc1879a864d595f8cf587ae9690f22
Author: Vadim Rutkovsky <vrutkovs redhat com>
Date:   Fri Mar 21 13:19:27 2014 +0100

    searchbar: don't crash if track doesn't have artist/album set
    
    https://bugzilla.gnome.org/show_bug.cgi?id=726721

 gnomemusic/searchbar.py |   14 ++++++++------
 1 files changed, 8 insertions(+), 6 deletions(-)
---
diff --git a/gnomemusic/searchbar.py b/gnomemusic/searchbar.py
index 9fb6bd8..f77beec 100644
--- a/gnomemusic/searchbar.py
+++ b/gnomemusic/searchbar.py
@@ -1,4 +1,5 @@
 from gi.repository import Gtk, Gd
+from gettext import gettext as _
 
 
 class Searchbar(Gd.Revealer):
@@ -27,13 +28,14 @@ class Searchbar(Gd.Revealer):
             search_string = self._search_entry.get_text().lower()
             media = model.get_value(itr, 5)
             searchable_fields = []
-            artist = None
+            artist = _("Unknown Artist")
+            album = _("Unknown Album")
             if media and media.get_url():
-                artist = media.get_artist()
-            if media and artist:
-                searchable_fields = [media.get_artist(),
-                                     media.get_album(),
-                                     media.get_title()]
+                if media.get_artist() is not None:
+                    artist = media.get_artist()
+                if media.get_album() is not None:
+                    album = media.get_album()
+                searchable_fields = [artist, album, media.get_title()]
             else:
                 searchable_fields = [model.get_value(itr, 2),
                                      model.get_value(itr, 3)]