The testsuite needs to be patched since we build with a recent version of
Mutagen and this test was written for an older one, where bit depths on WavPack
wasn't supported.
This is fixed upstream, but hasn't been released yet:
https://github.com/beetbox/mediafile/commit/d2fc3b59f77c515b02dfe7ad936f89264375d2b4
Index: python-mediafile/test/test_mediafile.py
===================================================================
--- python-mediafile.orig/test/test_mediafile.py
+++ python-mediafile/test/test_mediafile.py
@@ -907,7 +907,7 @@ class WavpackTest(ReadWriteTestBase, uni
         'bitrate': 109312,
         'format': u'WavPack',
         'samplerate': 44100,
-        'bitdepth': 0,
+        'bitdepth': 16,
         'channels': 1,
     }