setting original_date: yes and updating the library still lives year and original_year with different values

Here's my config if it may be useful

library: /data/Data/musiclibrary.blb
directory: /data/Music
plugins: lyrics fetchart embedart replaygain scrub lastgenre mbsync inline rewrite smartplaylist mbcollection convert info chroma fromfilename duplicates
lyrics:
    google_API_key: AIzaSyB8yiWYKHk10wfZ8x_lF8rHHI30WJutS4s
musicbrainz:
    user: bercio
    pass: *********
smartplaylist:
    playlist_dir: ~/.config/mpd/playlists
    relative_to: /data/Music
    playlists:
        - query: ''
          name: all.m3u
        - query: 'language:ita'
          name: musica.m3u
rewrite:
    artist Fabrizio .{0,4}Andr.[^\s]?: Fabrizio De André
item_fields:
    disc_and_track: u'%02i.%02i' % (disc, track) if
                    disctotal > 1 else u'%02i' % (track)
    creator: u'%s' % (albumartist) if
             composer == '' or composer == 'Unknown' or composer == albumartist or genre != 'classical'
             else u'%s/%s' % (composer, albumartist)
#    composer: u'%s' % (albumartist) if
#              composer == '' or composer == 'Unknown'
#              else u'%s' % (composer)
lastgenre:
    canonical: ''
replaygain:
    albumgain: yes
acoustid:
    apikey: XLwkkco7
replace:
    '[\\/]': _
    '^\.(?!\.\.)': _
    '[\x00-\x1f]': _
    '[<>:"\?\*\|]': _
    '\s+$': ''
    '\s': '_'
    '\.\.\.': '…'

per_disc_numbering: yes

original_date: yes                
match:
    strong_rec_thresh: 0.11
    medium_rec_thresh: 0.60
ignore: .* *~ *.txt
log:
    /var/log/beets.log
paths:
    default: $creator/$album%aunique{}/$disc_and_track-${title}
    singleton: $creator/Singles/$title
    comp: Compilations/$album%aunique{}/$disc_and_track-$title
    albumtype:soundtrack: %if{$creator,$creator,Soundtracks}/$album/$disc_and_track-$title

after a beet update year and original_year are still different:

$ beet info /data/Music/Björk/Vespertine/01.02-Cocoon.mp3 | grep year
             year: 2013
    original_year: 2001

beets version 1.3.1 on ubuntu 14.10

beetbox / beets

setting original_date: yes and updating the library still lives year and original_year with different values #1314