Symfony version(s) affected: latest 4.x

Description

Yesterday, after upgrading SF to the latest version, I start to get the following error:

Undefined class constant 'RESERVED_CHARACTERS' 

How to reproduce
My project is huge, I'm still trying to get the minimal code to regenerate this error. For now, add back to constant to the class will fix it.

Possible Solution

It seems like the constant is moved now to the Interface which causes the error?

Additional context

My PHP is on 7.2 if that makes any difference.