Bug#701044: updating severity, workarounds

[Daniel Pocock]

I've updated the severity of this bug to serious because

a) it corrupts the display in other applications using this library
(e.g. flactag)

b) it is not clear what impact it has on other applications if some
elements and attributes are not processed (flactag doesn't appear to
complete writing the tags to a FLAC file)

Even if fixing the bug/adding full support for these other
elements/attributes is not immediately possible, the severity of this
bug could probably be downgraded with some combination of the following
solutions:

- allow the applications to direct the log messages elsewhere (e.g. a
file or a window)

- MusicBrainz provides a legacy REST/HTTP API that works with this
version of the library for as long as the stable version of Debian is
supported (approximately 3 years from release)