[FIX] calendar: Calendar recurring start date is wrong

Steps to reproduce the bug:

- Create a recurring meeting, with a start date with time (not all day) (for example 09:00),
a duration (for example 5 hours) , each week for example on fridays, for 3 occurences.

-Save

Bug:
- The start_datetime ("Starting at") was increased with the duration of the meeting.

PS: The displayed start and stop in calendar view were computed in function "calendar_id2real_id"
with the virtual id.

opw:1858154

addons/calendar/calendar.py

@@ -1242,7 +1242,7 @@ def get_recurrent_ids(self, cr, uid, event_id, domain, order=None, context=None)
 
                 if [True for item in new_pile if not item]:
                     continue
-                result_data.append(self.get_search_fields(ev, order_fields, r_date=r_date))
+                result_data.append(self.get_search_fields(ev, order_fields, r_date=r_start_date))
 
         if order_fields:
             uniq = lambda it: collections.OrderedDict((id(x), x) for x in it).values()