This doesn't seem right to me. I think we want to make the same change 
we made to _kronolith_put - check if the event exists on the calendar 
we're importing to. I've done that in CVS.

Scenario:



An invitation is sent by USER_A to USER_B. USER_B accepts it in IMP 
and selects "Add to my calendar" the event attached. An new event is 
created in backend, but creator_id is USER_B, instead USER_A.



That behaviour doesn't occur when you import an entire iCalendar, 
throw WebDAV, for instance.



That happens because IMP uses calendar/import API method, which is 
focused to import only one event given in iCal format. When you 
publish a calendar throw WebDAV, calendar/put method is used.



So, I think that calendar/import should respect creator_id as 
calendar/put does.



I attach a patch to show a way to solve it. Mainly I use a similar 
instruction found in _kronolith_put function, line 556:



   // Don't change creator/owner.

   event->setCreatorId($existing_event->getCreatorId());