[3.0] Stop seeding a recurrence rule into the recurrence dates

[albertlast]

Description

Admin → Calendar → Holidays is an error page on every fresh install:

Failed to parse time string (FREQ=YEARLY) at position 0 (F):
The timezone could not be found in the database
                                        Sources/Calendar/Holiday.php:278

Two of the holidays the installer creates carry their own recurrence rule in the recurrence dates column. In Sources/Db/Schema/v3_0/Calendar.php:

'title'  => 'Cinco de Mayo',
'rrule'  => 'FREQ=YEARLY',
'rdates' => 'FREQ=YEARLY',     // ← should be ''

Same for Groundhog Day. Every other yearly holiday in that array has 'rdates' => '', and the 2.1 → 3.0 migration in HolidaysToEvents.php gets both of these right, so this is only the fresh-install seed.

rdates holds a list of dates. Holiday::list() takes the largest one and builds a \DateTimeImmutable out of it:

$max_rdate = max($row['rdates']);
$row['view_end'] = (new \DateTimeImmutable(substr($max_rdate, 0, strcspn($max_rdate, '/'))))->modify('+1 day');

so reading either row back throws, and the whole page goes with it.

The migration

3.0 is still Alpha, but a forum installed from an earlier alpha already has the two bad rows and would keep the broken page after upgrading. HolidayRecurrenceDates clears any rdates starting with FREQ= — a recurrence rule in that column can only have arrived this way, so the condition cannot catch a real date.

Checked

On the running forum, with the migration's UPDATE applied by hand: Admin → Calendar → Holidays renders and lists all 28 holidays, Cinco de Mayo and Groundhog Day among them, with nothing added to smf_log_errors.

That check needed #9405 in the tree as well — without it the same page dies a little later, in RecurrenceIterator, on the unrelated SMF\TimeInterval problem. The two fixes are independent; this one does not depend on that one to be correct, only to be observable.

Found by sweeping a stock forum's admin pages for fatals.

Issues References (Fixes|Related|Closes)

Related to #7933