calendar event with no DTEND causes DTSTART corruption
BEGIN:VCALENDAR
BEGIN:VEVENT
DTSTAMP:20171204T190108Z
DTSTART;VALUE=DATE:20201102
CLASS:PUBLIC
SUMMARY;LANGUAGE=de-AT:Allerseelen
TRANSP:TRANSPARENT
CATEGORIES:Feiertag
X-APPLE-UNIVERSAL-ID:4b6d2f05-680e-7b5e-043f-8cbd2ad082c0
END:VEVENT
END:VCALENDAR
calendar event with no DTEND causes DTSTART corruption