[FIX] calendar: add followers to recurrent events

default_get method of mail.wizard.invite model uses
the key 'default_res_id' to retrieve the res_id of the record
to add the followers.

In the case of recurrent events, virtual ids are used, and
the conversion from virtual ids to real ids is needed.

addons/calendar/calendar.py

@@ -1825,6 +1825,8 @@ class invite_wizard(osv.osv_memory):
         '''
         in case someone clicked on 'invite others' wizard in the followers widget, transform virtual ids in real ids
         '''
+        if 'default_res_id' in context:
+            context['default_res_id'] = get_real_ids(context['default_res_id'])
         result = super(invite_wizard, self).default_get(cr, uid, fields, context=context)
         if 'res_id' in result:
             result['res_id'] = get_real_ids(result['res_id'])