Why is it "clearly" an error? This syntax has been around forever and is widely used by code golfers, so if it were unintentional, I'm sure the Python devs would've fixed it by now.
It no longer matters if it was originally unintentional. If it's in active use now, so even if was originally by accident it cannot be fixed without breaking backwards compatibility.
Eh, python breaks backwards compatibility between versions all the time. And I don't know if "it's used by codegolfers" is a legitimate reason to keep a language feature.
That said, I have a really hard time imagining this issue coming up in regular usage of the language so I don't really have much of an opinion should they choose to keep or drop it.