stack trace for embedded art import in beet import

Sending event: import_task_files
Traceback (most recent call last):
  File "/usr/local/bin/beet", line 9, in <module>
    load_entry_point('beets==1.3.11', 'console_scripts', 'beet')()
  File "/Library/Python/2.7/site-packages/beets-1.3.11-py2.7.egg/beets/ui/__init__.py", line 953, in main
    _raw_main(args)
  File "/Library/Python/2.7/site-packages/beets-1.3.11-py2.7.egg/beets/ui/__init__.py", line 943, in _raw_main
    subcommand.func(lib, suboptions, subargs)
  File "/Library/Python/2.7/site-packages/beets-1.3.11-py2.7.egg/beets/ui/commands.py", line 868, in import_func
    import_files(lib, paths, query)
  File "/Library/Python/2.7/site-packages/beets-1.3.11-py2.7.egg/beets/ui/commands.py", line 845, in import_files
    session.run()
  File "/Library/Python/2.7/site-packages/beets-1.3.11-py2.7.egg/beets/importer.py", line 316, in run
    pl.run_parallel(QUEUE_SIZE)
  File "/Library/Python/2.7/site-packages/beets-1.3.11-py2.7.egg/beets/util/pipeline.py", line 347, in run
    self.coro.send(msg)
  File "/Library/Python/2.7/site-packages/beets-1.3.11-py2.7.egg/beets/util/pipeline.py", line 160, in coro
    task = func(*(args + (task,)))
  File "/Library/Python/2.7/site-packages/beets-1.3.11-py2.7.egg/beets/importer.py", line 1357, in manipulate_files
    session=session,
  File "/Library/Python/2.7/site-packages/beets-1.3.11-py2.7.egg/beets/importer.py", line 652, in manipulate_files
    plugins.send('import_task_files', session=session, task=self)
  File "/Library/Python/2.7/site-packages/beets-1.3.11-py2.7.egg/beets/plugins.py", line 465, in send
    result = handler(**args)
  File "/Library/Python/2.7/site-packages/beets-1.3.11-py2.7.egg/beetsplug/fetchart.py", line 355, in assign_art
    album.set_art(path, not src_removed)
  File "/Library/Python/2.7/site-packages/beets-1.3.11-py2.7.egg/beets/library.py", line 987, in set_art
    artdest = util.unique_path(artdest)
  File "/Library/Python/2.7/site-packages/beets-1.3.11-py2.7.egg/beets/util/__init__.py", line 491, in unique_path
    new_path = '%s.%i%s' % (base, num, ext)
UnicodeDecodeError: 'ascii' codec can't decode byte 0xe2 in position 62: ordinal not in range(128)