Yes, `metatype == &PyType_Type` makes sure that only `type` itself is valid for the one-argument part, whereas subclasses can also do so right now. I clarified that in a comment in the new patch, so that someone doesn't accidentally revert this, thinking PyType_CheckExact is fine.

Before the patch:

>>> type(1, 2, 3)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: type() argument 1 must be str, not int

After the patch:

>>> type(1, 2, 3)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: type.__new__() argument 1 must be str, not int
>>> class X(type): pass
...
>>> X(1)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: type.__new__() argument 1 must be str, not int