Reverted the last change afterall. The reason is that the most obvious way
to work around this problem is something like this:
Calendar.ISO.Day stepped = day->add (n, Calendar.ISO.Month());
int m = stepped->month_no();
while (stepped->month_no() == m && stepped->month_day() < day->month_day())
stepped -= Calendar.ISO.Day();
and that would break thoroughly by this fix. The fix will only be in
versions >= 7.7 with compat goo.