parse_vevents used to leave raw_uid: None for any VEVENT with no UID
line, which the storage layer's unique index exempts from dedup -- so
that event duplicated on every re-import forever. Falls back to
content_uid (subject|organizer|starts_at|ends_at) so re-parsing the same
source resolves to the same key. Also fixes ymd_digits, the per-occurrence
dedup-key suffix for expanded recurring events, to format in UTC instead
of the machine's local timezone -- it could otherwise compute a different
date (and therefore a different key) for the same occurrence across a DST
transition or timezone change between imports.
iamdoubz
3214bd2740