Sigh.  You are right.  I will close this tomorrow.


This also means that 'set()' is not guaranteed to return an empty built-in set. I did think of this workaround for that:
>>> (empty:={None}).clear()
>>> empty
set()
 
Go ahead and propose something on python-ideas if you want, pointing out that only displays (and comprehensions) are guaranteed to result in a builtin.