Calendar Event displays errenous end date

[Alpha1]

I yearly 1 day event was imported from vbulletin. The event was added in 2013.
Instead of importing it as a 1 day event is was imported as:
Start: 2013-04-19 12AM
End: 2037-04-19 12AM

So instead of a 1 day event is has become a multi-year event.

 

[Alpha1]

I have a recurring event: 19 April to 20 April. When I edit the event it displays these dates.
But on the event page it displays as this:
Apr 19, 2019 at 12:00 AM → Apr 20, 2013 at 12:00 AM

The event was added in 2013.

 

[Naz]

I've made some improvements to the vB importer which should handle cases like this better.