mpdstats: mpd events are processed twice

[rafi]

Running beet -v mpdstats shows that mpd events are processed twice, for example:

mpdstats: playing /mnt/media/music/10 Her Majesty.mp3
Sending event: database_change
mpdstats: updated: last_played = 1400247006 [/mnt/media/music/10 Her Majesty.mp3]
mpdstats: playing /mnt/media/music/10 Her Majesty.mp3
Sending event: database_change
mpdstats: updated: last_played = 1400247006 [/mnt/media/music/10 Her Majesty.mp3]
Sending event: database_change

[brunal]

This does not happen for all events, and depends on the sequence of commands executed. Example following. Music redacted for terseness (it's actually some awesome Grateful Dead).

# standard stuff
user configuration: /home/bru/.config/beets/config.yaml
data directory: /home/bru/.config/beets
Sending event: pluginload
library database: /home/bru/.beetsmusic.blb
library directory: /home/bru/Musique
Sending event: library_opened
mpdstats: connecting to localhost:6600
mpdstats: playing /home/bru/Musique/A.mp3
Sending event: database_change
mpdstats: updated: last_played = 1420711398 [/home/bru/Musique/A.mp3

# the song is now naturally over
Sending event: database_change
mpdstats: updated: play_count = 1 [/home/bru/Musique/A.mp3]
mpdstats: played /home/bru/Musique/A.mp3
Sending event: database_change
mpdstats: updated: rating = 0.6875 [/home/bru/Musique/A.mp3]
mpdstats: playing /home/bru/Musique/B.mp3
Sending event: database_change
mpdstats: updated: last_played = 1420711519 [/home/bru/Musique/B.mp3]
mpdstats: playing /home/bru/Musique/B.mp3
Sending event: database_change
mpdstats: updated: last_played = 1420711522 [/home/bru/Musique/B.mp3]
# it is happening twice indeed. Now I'm skipping to the next song

Sending event: database_change
mpdstats: updated: skip_count = 1 [/home/bru/Musique/B.mmp3]
mpdstats: skipped /home/bru/Musique/B.mp3
Sending event: database_change
mpdstats: updated: rating = 0.3125 [/home/bru/Musique/B.mp3]
mpdstats: playing /home/bru/Musique/C.mp3
Sending event: database_change
mpdstats: updated: last_played = 1420711578 [/home/bru/Musique/C.mp3]
# happened only once! Now I'm skipping back

Sending event: database_change
mpdstats: updated: skip_count = 1 [/home/bru/Musique/C.mp3]
mpdstats: skipped /home/bru/Musique/C.mp3
Sending event: database_change
mpdstats: updated: rating = 0.3125 [/home/bru/Musique/C.mp3]
mpdstats: playing /home/bru/Musique/B.mp3
Sending event: database_change
mpdstats: updated: last_played = 1420711592 [/home/bru/C.mp3]
# happened only once!
# and again when I let it play naturally

Therefore 'playing' (i.e. on_play(=) is incorrectly triggered a second time on natural music advancement...

[brunal]

mpd responds to the command idle only once on user-requested song change, and twice on "natural" song change. See specification of the command: http://www.musicpd.org/doc/protocol/command_reference.html.
Patch incoming.