A one-time event opened for editing said "this is a recurring event —
changes apply to the whole series", and deleting one offered to delete
all occurrences of an event that has exactly one.
Three places asked whether an event had a baseEventId and took that for
recurrence. It isn't: the calendar loads its range with expandRecurrences,
and Stalwart puts a baseEventId on everything it returns that way, a
one-off pointing at itself included. The mock never sets the field at
all, which is why this only showed up against a real server.
They now share isRecurring(), which asks about recurrence rules, and
treats a base that is some other event as an occurrence of a series too
— so an expanded instance that travels without its rules is still
described honestly on the way to being deleted.
Fixes#25
jcoffey-dev
8b22ea9aab