If anything,#16733 seems to prove that we need to keep the check inlonger. Python 2 was only just let go this year.

But the point is that the check is actually not doing its job, because if you're running setup.py in an old Python you get the syntax error even before the check runs.

The point is to fix that other syntax error and not to add more incompatibility?

The point is to fix that other syntax error

This is bound to break regularly again unless we actually test that.
If we care about this use case I would suggest that we just move everything to setupext.py with just a version check in setup.py before importing setupext (which is fine too; do you agree with this plan?).

The jquery stuff and command definitions surely should go into setupext.py; as well as the package collection. However I would leavesetup() in place. That's where people expect it.

Since we got another report about theSyntaxError, I don't think we're ready to be removing this check. I've opened the above-mentioned PR to fix the syntax errors instead. I'm going to close this for now.

Sounds fair.