GlideDateTime's addDays not working as expected

[Sameer18]

The GlideDateTime's addDays not working as expected. This function is not returning correct value for time

In the below example I am taking time of 90 days back from current date. However the function is returning correct value till '-78' days but not working as expected for values greater than 78.

I am wondering if this is bug in service now or am I missing any step here.

Sample Code

var toDateTime = new GlideDateTime(gs.now());
	var gtime = new GlideTime();
	gtime.setValue("23:59:59");
	toDateTime.add(gtime);

var fromDateTime = new GlideDateTime(toDateTime.now());
fromDateTime.addDays(-90); //fromDateTime.addDays(-78); works fine till 78

gs.log("From Date Time " + fromDateTime);
gs.log("To Date Time " + toDateTime);

Output:

*** Script: From Date Time 2019-02-27 00:59:59
*** Script: To Date Time 2019-05-27 23:59:59
*** Script: Expected From Date Time 2019-02-27 23:59:59

Instead of returning  23:59:59 function is returning  00:59:59

[MD ARSHAD ALAM]

i made so much logic every thing get failed other than addDaysUTC. Thanks @Oleg