This particular breakage is explicitly listed in PEP 560, see an example
with List and List[int] in
https://www.python.org/dev/peps/pep-0560/#backwards-compatibility-and-impact-on-users-who-don-t-use-typing
In general, isinstance() with typing types should be avoided when possible
(Mark Shannon wh
First, the typing module is still provisional, so there is no strict
backwards compatibility guarantee.
With that out of the way, I can reproduce your problem, and I assume it's
caused by the implementation of PEP 560, which is meant to speed up the
typing module (among other goals).
I'm wonderin
