badfiles: Python 3 compatibility

Discovered while working on beetbox#2428 that we were using an implicit bytes-to-str
conversion on the extension. This broke dict lookup on Python 3.

Author: sampsyo

beetsplug/badfiles.py

@@ -94,7 +94,7 @@ def check_bad(self, lib, opts, args):
                     ui.colorize('text_error', dpath)))
 
             # Run the checker against the file if one is found
-            ext = os.path.splitext(item.path)[1][1:]
+            ext = os.path.splitext(item.path)[1][1:].decode('utf8', 'ignore')
             checker = self.get_checker(ext)
             if not checker:
                 self._log.debug(u"no checker available for {}", ext)

docs/changelog.rst

@@ -32,6 +32,7 @@ Fixes:
 * :doc:`/plugins/mpdstats`: Fix Python 3 compatibility. The plugin also now
   requires version 0.4.2 or later of the ``python-mpd2`` library. :bug:`2405`
 * :doc:`/plugins/mpdstats`: Improve handling of mpd status queries.
+* :doc:`/plugins/badfiles`: Fix Python 3 compatibility.
 
 
 1.4.3 (January 9, 2017)