Error when converting Google Calendar

Hi,

When trying to convert a calendar [1] created with Google Calendar
using fromIcal.py [2] script, I have an error with the following line:

ATTENDEE;CUTYPE=INDIVIDUAL;ROLE=REQ-PARTICIPANT;PARTSTAT=NEEDS-ACTION;CN=Al
 exandre Passant;X-NUM-GUESTS=0:MAILTO:apassant@gmail.com

(even with --x option)

It can be solved adding X-NUM-GUEST at line 642 of the script, but I
don't think this is the most elegant way.
BTW, does this line is ok regarding iCal specs ?

Best,

Alex.

[1] http://www.google.com/calendar/ical/apassant@gmail.com/public/basic.ics
[2] http://www.w3.org/2002/12/cal/fromIcal.py