Date exclude save wiping out dates and exclusions when saving

Looked into this issue a bit more.

This scenario looks like its only possible when the rules given DO NOT match the 'custom' recurrence option in guessRecurrenceOptionFromRrule, such as when you have a clean rrule like FREQ=DAILY, with EXDATES, and the occurrence model is NOT interacted with.

Right now, whenever you interact with the occurrence model at all, when you close the modal with the 'Done' button (not the X quit button), the recurrence option is always set to 'custom' in transferModalToFormStateCallback:

      $input = &$form_state->getUserInput();
      // After closing modal, switch dropdown to custom setting.
      $input[$fieldName][$delta]['recurrence_option'] = 'custom';

I think what needs to happen here is the guesser needs to match the transferModel behaviour by setting to custom if there are any exdates.

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On the DateRecurModularSierraWidget::validateModularWidget changes introduced by 10, I wasnt particularly happy with these changes. They look quite brittle, tied to a particular RRULE style. So this has been discarded.

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The change proposed by #5 does not look relevant to this issue, as I was able to reproduce and fix the primary issue reported by this issue without the proposed modification. This change has been discarded. Please create a new issue if you find your bug persists.

Committed with modifications, please test, thanks.

Automatically closed - issue fixed for 2 weeks with no activity.

If you use PHP 7.x and get the PHP error, "TypeError: explode() expects parameter 2 to be string, bool given in explode()", apply this patch.

This patch works with version 3.1.0

I had to manually massage the patch in 21 to get it to work - it needs a re-roll (still against 3.1.0), but it also needs a trailing line break. I've attached my locally modified patch which should apply, but it really needs a proper re-roll (at least until we get a new release).