Improve handling of file system encoding errors

[tkem]

Currently, if a directory path cannot be decoded when browsing "Folders", an exception is raised, and the parent folder will appear to be empty. This is usually the case when mopidy is running with the "POSIX" locale, i.e. an incomplete/erroneous locale setup (such as on Pi MusicBox RC5.1). It might be better to follow the json library, and explicitly decode directory paths (and probably track names) using sys.getfilesystemencoding() with errors=replace. Note that this will not automagically provide support for Unicode directory paths, but will result in less cryptic behavior (i.e. users who see non-ASCII characters replaced with something funny are more likely to look into locale and filesystem settings).

[jodal]

:+1:

[tkem]

See also https://discuss.mopidy.com/t/network-folders-are-showing-up-empty-in-musicbox-0-5-1rc/315

[tkem]

The exception is actually raised in sorted(os.listdir(...)), since os.listdir returns byte strings on Python 2 if the file name cannot be decoded, and sorted tries to decode using ascii for mixed string sequences. Or so it seems.