Fix https://gna.org/bugs/index.php?23065

src/sound.cpp

@@ -596,6 +596,8 @@ void play_music_config(const config &music_node)
 	if (track.immediate()) {
 		current_track = track;
 		play_music();
+	} else if (!track.append()) { // Make sure the current track is finished
+		current_track.set_play_once(true);
 	}
 }