Fetchart: Wikipedia source is not unicode-ready

[wisp3rwind]

Fails when formatting artist and title into the basestring request. Beets was a few commits behind master, but I don't think there've been any changes to fetchart since.

The offending album was
http://musicbrainz.org/release/a2f9ef1e-dc73-4054-94f4-5b341660e73e

Traceback (most recent call last):
  File "/usr/bin/beet", line 9, in <module>
    load_entry_point('beets==1.3.18', 'console_scripts', 'beet')()
  File "/usr/lib/python2.7/site-packages/beets/ui/__init__.py", line 1247, in main
    _raw_main(args)
  File "/usr/lib/python2.7/site-packages/beets/ui/__init__.py", line 1237, in _raw_main
    subcommand.func(lib, suboptions, subargs)
  File "/usr/lib/python2.7/site-packages/beets/ui/commands.py", line 965, in import_func
    import_files(lib, paths, query)
  File "/usr/lib/python2.7/site-packages/beets/ui/commands.py", line 942, in import_files
    session.run()
  File "/usr/lib/python2.7/site-packages/beets/importer.py", line 336, in run
    pl.run_parallel(QUEUE_SIZE)
  File "/usr/lib/python2.7/site-packages/beets/util/pipeline.py", line 248, in run
    self._run()
  File "/usr/lib/python2.7/site-packages/beets/util/pipeline.py", line 346, in _run
    out = self.coro.send(msg)
  File "/usr/lib/python2.7/site-packages/beets/util/pipeline.py", line 191, in coro
    func(*(args + (task,)))
  File "/usr/lib/python2.7/site-packages/beets/importer.py", line 1389, in plugin_stage
    func(session, task)
  File "/usr/lib/python2.7/site-packages/beets/plugins.py", line 123, in wrapper
    return func(*args, **kwargs)
  File "/usr/lib/python2.7/site-packages/beetsplug/fetchart.py", line 755, in fetch_art
    candidate = self.art_for_album(task.album, task.paths, local)
  File "/usr/lib/python2.7/site-packages/beetsplug/fetchart.py", line 825, in art_for_album
    for candidate in source.get(album, extra):
  File "/usr/lib/python2.7/site-packages/beetsplug/fetchart.py", line 491, in get
    artist=album.albumartist.title(), album=album.album)
UnicodeEncodeError: 'ascii' codec can't encode character u'\xed' in position 5: ordinal not in range(128)

[jackwilsdon]

After doing some tests, it seems that the root cause of this is that SPARQL_QUERY is an ASCII string where as either album.albumartist.title() or album.album is a Unicode string.

A simple fix would be to decode SPARQL_QUERY as Unicode, making it into a Unicode string:

--- fetchart.py
+++ fetchart.py
@@ -487,7 +487,7 @@
             params={
                 'format': 'application/sparql-results+json',
                 'timeout': 2500,
-                'query': self.SPARQL_QUERY.format(
+                'query': self.SPARQL_QUERY.decode('utf-8').format(
                     artist=album.albumartist.title(), album=album.album)
             },
             headers={'content-type': 'application/json'},

I'm not sure if this is a good way to fix this, as it may just move the error elsewhere. I'm sure @sampsyo has a better method for fixing this.

[sampsyo]

Thanks! This probably arose recently during the unicode_literals transition. Fixed by using a Unicode literal for the query.