calcurse-caldav: Importing of appointments with length 0 fails

[mowgli]

Version information.
4.8.1-r1 in gentoo

Bug description.
When trying to import my caldav (radicale) into calcurse I get the the following error when importing appointments like birthdays that have DTSTART and DTEND at the very exact same moment in time.

VEVENT [21]: end must be later than start.

or

VEVENT [71]: end must be later than start.

Reproduce.
Always.

Expected Behavior.
Imported events

[lfos]

@mowgli - Thanks for the bug report. It's my understanding that such an appointment violates the iCal specification.

From https://www.kanzaki.com/docs/ical/dtend.html:

The value MUST be later in time than the value of the "DTSTART" property.

Do you happen to know which program/app generated the appointment? If it's widely used, we may want to relax our checks, even if that means we'll parse non-compliant iCal appointments.