Error converting SoundFont from MuseScore

I'm encountering an error when trying to use rnsutils to convert the Fluid Soundfont included with MuseScore to xrni. The SoundFont file is here:

https://github.com/musescore/MuseScore/blob/master/share/sound/FluidR3Mono_GM.sf3

Here's the error I'm seeing:

Reading instruments from 'FluidR3Mono_GM.sf3'
Traceback (most recent call last):
  File "/usr/local/bin/sf2toxrni", line 11, in <module>
    sys.exit(main())
  File "/Library/Python/2.7/site-packages/rnsutils/sf2toxrni.py", line 295, in main
    for instrument_idx, sf2_instrument in enumerate(sf2.instruments):
  File "/Library/Python/2.7/site-packages/sf2utils/sf2parse.py", line 125, in instruments
    self._instruments = self.build_instruments()
  File "/Library/Python/2.7/site-packages/sf2utils/sf2parse.py", line 151, in build_instruments
    return [Sf2Instrument(self._raw.pdta, idx, self) for idx in range(len(self._raw.pdta['Inst']))]
  File "/Library/Python/2.7/site-packages/sf2utils/instrument.py", line 20, in __init__
    self.bag_size = hydra_header['Inst'][idx + 1].bag - self.bag_idx
IndexError: list index out of range