Listen unusable after connection to last.fm failed

I tried to connect to a last.fm station. Listen said: "Connected, Station found" but did not play any music.
Now I was unable to change to a different track, because the change operation tried to delete the "#stream_offset" key. Here is the traceback:

Traceback (most recent call last):
  File "/usr/lib/listen/widget/playlist.py", line 221, in on_activated
    self.play_selected()
  File "/usr/lib/listen/widget/playlist.py", line 225, in play_selected
    Player.play_new(model[rows[0]][0])
  File "/usr/lib/listen/player/__init__.py", line 243, in play_new
    self.set_song(song, True, crossfade, seek)
  File "/usr/lib/listen/player/__init__.py", line 261, in set_song
    LastFmPlayer.stop()
  File "/usr/lib/listen/lastfm_player.py", line 262, in stop
    ListenDB.del_property(self.song,["#stream_offset","album","artist","track_url","#duration","title"])
  File "/usr/lib/listen/library.py", line 499, in del_property
    for key in keys: del song[key]
KeyError: '#stream_offset'

I patched the file

/usr/lib/listen/library.py

to

 493 def del_property(self, song, keys):
 494 if not song: return False
 495 self._dirty = True
 496 type = song.get_type()
 497 old_keys_values = {}
 498 [ old_keys_values.update({key:song.get_sortable(key)}) for key in song.keys() if key in keys]
 499 for key in keys:
 500 if key in song.keys():
 501 del song[key]
 502 song.sanitarize()
 503 self.__condition.acquire()
 504 self.__queued_signal["changed"].setdefault(type, [])
 505 self.__queued_signal["changed"][type].append((song, old_keys_values))
 506 self.__condition.release()

and now I can change the songs again, but last.fm still is not working.

best regards,

Brian