using utcOffset setter with keepLocalTime = true results in inconsistent date

[icguy]

Describe the bug
if .utcOffset setter is called with the second param (keepLocalTime) set to true weird things start to happen:

• the toString() function will return incorrect results.
• diff() function will work incorrectly
• the format() function however returns the correct result

Reproduction on dayjs website in chrome js console:

Expected behavior
The format and toString functions should return consistent results, being the same date, diff should return zero.

Information

• OS: Windows
• Browser Chrome 88.0.4324.190
• Time zone: CET

[CoreyKovalik]

Hey @icguy 👋

I ran into this at my company, where we have one app using luxon and one using dayjs. seems that luxon does not make this error. I noticed you posted this on Mar 10, which is close to DST in spring. DST is a week away now for fall on the 7th. 😅 ....

I wonder how many people are running into bugs like these around DST every year!