Please describe the problem:
When trying to play any type of last.fm stream I get just "Could not determine type of stream." and nothing is playing. The official player works, so it doesn't seem like a problem on their side... Below is some debug output from rhythmbox --debug (I've anonimized the session key):
(11:11:41) [0xcfd960] [start_sink] rb-player-gst-xfade.c:2302: starting sink
(11:11:41) [0xcfd960] [start_sink] rb-player-gst-xfade.c:2332: silence bin is now in state PAUSED
(11:11:41) [0xcfd960] [start_sink] rb-player-gst-xfade.c:2339: adder is now in state PAUSED
(11:11:41) [0xcfd960] [start_sink] rb-player-gst-xfade.c:2346: output bin is now in state PAUSED
(11:11:41) [0xcfd960] [start_sink] rb-player-gst-xfade.c:2351: unpausing sink
(11:11:41) [0xcfd960] [start_sink] rb-player-gst-xfade.c:2391: sink playing
(11:11:41) [0xcfd960] [rb_player_gst_xfade_play] rb-player-gst-xfade.c:2956: playing stream xrblastfm://87.117.229.85:80/last.mp3?Session=XXXX, crossfade -1
(11:11:41) [0xcfd960] [rb_player_gst_xfade_play] rb-player-gst-xfade.c:2970: stream xrblastfm://87.117.229.85:80/last.mp3?Session=XXXX is prerolling; will start playback once prerolling is complete -> PREROLL_PLAY
(11:11:41) [0x6c9500] [notify_playing_idle] rb-shell-player.c:608: emitting playing notification: 0
(11:11:41) [0x6c9500] [show_controls] rb-visualizer-plugin.c:826: showing controls
(11:11:41) [0x6c9500] [rb_shell_player_sync_buttons] rb-shell-player.c:2666: syncing with source 0x1381010
(11:11:41) [0x1852440] [stream_queue_probe_cb] rb-player-gst-xfade.c:1559: current network buffer level: 0; threshold 65536 - 0%
(11:11:41) [0x6c9500] [get_times_and_stream] rb-player-gst-xfade.c:2251: not playing
(11:11:41) [0x1851850] [stream_queue_threshold_cb] rb-player-gst-xfade.c:1571: queue running - removing pad probe, running signal handler
(11:11:41) [0x6c9500] [rb_shell_player_error] rb-shell-player.c:2962: playback error while playing: Could not determine type of stream.
(11:11:41) [0x6c9500] [rb_shell_player_set_playing_source_internal] rb-shell-player.c:2732: setting playing source to (nil)
(11:11:41) [0x6c9500] [rb_shell_player_set_playing_source_internal] rb-shell-player.c:2755: source is already playing, stopping it
(11:11:41) [0x6c9500] [rb_shell_player_stop] rb-shell-player.c:2800: stopping
(11:11:41) [0x6c9500] [unlink_and_dispose_stream] rb-player-gst-xfade.c:1233: stopping stream xrblastfm://87.117.229.85:80/last.mp3?Session=bc44aa63195f8beaaf9e9efdf4cfcb5f
(11:11:41) [0x6c9500] [dump_stream_list] rb-player-gst-xfade.c:471: stream list is empty
(11:11:41) [0x6c9500] [rb_shell_player_sync_with_source] rb-shell-player.c:2563: playing source: (nil), active entry: (nil)
(11:11:41) [0x6c9500] [get_times_and_stream] rb-player-gst-xfade.c:2251: not playing
(11:11:41) [0x6c9500] [rb_shell_set_window_title] rb-shell.c:2083: clearing title
(11:11:41) [0x6c9500] [rb_shell_player_get_playing_song_duration] rb-shell-player.c:2926: Did not get playing entry : return -1 as length
(11:11:41) [0x6c9500] [show_controls] rb-visualizer-plugin.c:826: showing controls
(11:11:41) [0x6c9500] [rb_shell_player_get_playing_song_duration] rb-shell-player.c:2926: Did not get playing entry : return -1 as length
(11:11:41) [0x6c9500] [rb_header_sync] rb-header.c:355: syncing with entry = (nil)
(11:11:41) [0x6c9500] [rb_header_sync] rb-header.c:426: not playing
(11:11:41) [0x6c9500] [rb_shell_player_get_playing_song_duration] rb-shell-player.c:2926: Did not get playing entry : return -1 as length
(11:11:41) [0x6c9500] [rb_lastfm_song_changed_cb] rb-lastfm-source.c:1320: non-lastfm entry being played
(11:11:41) [0x6c9500] [show_controls] rb-visualizer-plugin.c:826: showing controls
(11:11:41) [0x6c9500] [rb_shell_player_sync_buttons] rb-shell-player.c:2666: syncing with source 0x1381010
(11:11:41) [0x6c9500] [rb_shell_player_sync_with_source] rb-shell-player.c:2563: playing source: (nil), active entry: (nil)
(11:11:41) [0x6c9500] [get_times_and_stream] rb-player-gst-xfade.c:2251: not playing
(11:11:41) [0x6c9500] [rb_shell_set_window_title] rb-shell.c:2083: clearing title

Steps to reproduce:
Just try to play any last.fm stream.

Actual results:


Expected results:


Does this happen every time?
Yes on multiple machines with different distros and rhythmbox 0.11.2 and 0.11.3

Other information:
It's also reported in launchpad under https://bugs.launchpad.net/ubuntu/+source/rhythmbox/+bug/163519