on a system w/o python3

[snippsat]

but lately ... 2.x is dead.

That's true,i would not have make any effort at all to support Python 2,if should release some Python stuff today.
Also 3.6(the biggest python 3 release with 16 new PEP) and core change to dictionary smaller/faster and ordered.
This really break a lot,so no effort should be used to port back to 2 (some have done it with f-string sigh)

It's also good that big library make a clear statement of the way forward.
Like Django 2.0 soon to be released(no support for Python 2 at all) and Requests(yellow statement).

NoteThe use of Python 3 is highly preferred over Python 2.
Consider upgrading your applications and infrastructure if you find yourself still using Python 2 in production today.
If you are using Python 3, congratulations — you are indeed a person of excellent taste. —Kenneth Reitz