musicxml2ly crash when reading breves

[David Fletcher]

When I run musicxml2ly on a music XML file containing breves e.g.

        <duration>16</duration>
        <voice>1</voice>
        <type>breve</type>

it crashes with the diagnostic as follows:
Traceback (most recent call last):
  File "C:\Program Files\LilyPond\usr\bin\musicxml2ly.py", line 675, in ?
    main()
  File "C:\Program Files\LilyPond\usr\bin\musicxml2ly.py", line 672, in main
    voices = convert (args[0], options)
  File "C:\Program Files\LilyPond\usr\bin\musicxml2ly.py", line 648, in convert
   print_voice_definitions (printer, voices)
  File "C:\Program Files\LilyPond\usr\bin\musicxml2ly.py", line 539, in
print_voice_definitions
    voice.print_ly (printer)
  File "out/musicexp.py", line 399, in print_ly
  File "out/musicexp.py", line 438, in print_ly
  File "out/musicexp.py", line 569, in print_ly
  File "out/musicexp.py", line 137, in print_ly
  File "out/musicexp.py", line 129, in ly_expression
ValueError: negative shift count

Whilst Lilypond sems to know about breves and longas (though, sady not maximas)
I suspect that musicxml2ly does not.  When I patched out the breves it converted
the file but without lyrics  - should it handle them?.

Sadly, runnng under Windows XP Lilypond 2.10.33 fails to typeset the result,
without comment.  Is there a way to find out what its problem is - the -V option
or --verpose seem to have no effect