fix calendar when event has no DTEND record

CHANGELOG.md

@@ -23,6 +23,7 @@ _This release is scheduled to be released on 2021-01-01._
 - Fix calendar fetcher subsequent timing (#2160)
 - Rename Greek translation to correct ISO 639-1 alpha-2 code (gr > el). (#2155)
 - Add a space after icons of sunrise and sunset (#2169)
+- Fix calendar when no DTEND record found in event, startDate overlay when endDate set (#2177)
 
 ## [2.13.0] - 2020-10-01
 

modules/default/calendar/calendarfetcher.js

@@ -117,7 +117,8 @@ const CalendarFetcher = function (url, reloadInterval, excludedEvents, maximumEn
 						endDate = startDate.clone().add(moment.duration(event.duration));
 					} else {
 						if (!isFacebookBirthday) {
-							endDate = startDate;
+							// make copy of start date, separate storage area
+							endDate = moment(startDate.format("x"), "x");
 						} else {
 							endDate = moment(startDate).add(1, "days");
 						}