Unexpected UnicodeDecodeError

[Lukasa]

Encountered the following traceback when fuzzing hyper-h2:

Traceback (most recent call last):
  File "script.py", line 10, in <module>
    c.receive_data(sys.stdin.read())
  File "/Users/cory/tmp/fuzz-results/env/lib/python2.7/site-packages/h2/connection.py", line 892, in receive_data
    events.extend(self._receive_frame(frame))
  File "/Users/cory/tmp/fuzz-results/env/lib/python2.7/site-packages/h2/connection.py", line 915, in _receive_frame
    frames, events = self._frame_dispatch_table[frame.__class__](frame)
  File "/Users/cory/tmp/fuzz-results/env/lib/python2.7/site-packages/h2/connection.py", line 956, in _receive_headers_frame
    headers = self.decoder.decode(frame.data)
  File "/Users/cory/tmp/fuzz-results/env/lib/python2.7/site-packages/hpack/hpack.py", line 351, in decode
    return [(n.decode('utf-8'), v.decode('utf-8')) for n, v in headers]
  File "/Users/cory/tmp/fuzz-results/env/lib/python2.7/encodings/utf_8.py", line 16, in decode
    return codecs.utf_8_decode(input, errors, True)
UnicodeDecodeError: 'utf8' codec can't decode byte 0x87 in position 1: invalid start byte

It would be better if a HPACK-specific exception were thrown here.