Thanks for calling this to my attention.
It looks like the new default behavior could cause some confusion for users who are returning to the site via an external link and wonder why their login does not persist in that situation until they follow an internal link on the site or log in again. But the experience will not be broken, and you could certainly log in again.
For 3.x we might choose to use the Google-approved double-cookie approach described in that article if we want to continue to have long-persisting sessions. We are trying to freeze the 2.x feature set in order to focus on 3.x, but it’s possible we may have to deliver that tweak for 2.x as well. The best practice, though, might be to say that if the user really wants their editing login to be easy at the expense of some security they should be using a password manager, not relying on cookies.