Initial occurence of 'diary-anniversary' in calendar

[Ulf Jasper]

Anniversary entries like

    %%(diary-anniversary 4 4 2016) Mark My Diary

will show up in the calendar only from 4 4 2017 on, i.e. one year after
the actual event.  The initial occurrence of an anniversary (4 4 2016)
does not get marked in the calendar.  Why is that?

(Changing this behaviour would fix bug#23100 which results from that
fact that icalendar.el considers 'diary-anniversary' to be equivalent to
a YEARLY ical event.)

Making the initial occurrence of an anniversary show up seems natural to
me.  So I would like to implement that.  But maybe I am missing
something here.  Am I?

Best,
Ulf