curds: Previous playlist should send playlist-changed

Otherwise we won't update the row in the sidebar with the number of
tracks played.

Signed-off-by: Anna Schumaker <Anna@NoWheyCreamery.com>

curds/playlist/previous.py

@@ -11,6 +11,7 @@ class PreviousPlaylist(playlist.Playlist):
             self.list.insert(0, track)
             self.current = 0
             notify.notify("add-track", self, track, 0)
+            self.changed()
 
     def set_loop(self, loop):
         return playlist.Playlist.set_loop(self, False)