Missing update method on the CaseInsensitiveDict

[Fokko]

We got mypy errors after the release 6 hours ago:

communication/slack/tasks.py:39: error: "CaseInsensitiveDict?[builtins.str]" has no attribute "update"

This is when we do (simplified):

session = requests.Session()
session.headers.update({"Authorization": f"Bearer {access_token}"})

Also part of the docs: https://docs.python-requests.org/en/master/user/advanced/

I think the CaseInsensitiveDict should also contain the .update() method. Will open a PR in a second.

[AlexWaygood]

Thanks! The issue isn't that CaseInsensitiveDict doesn't have a .update() method, however — it does, it inherits it from MutableMapping. The issue is that CaseInsensitiveDict is currently marked as a TypeAlias assignment following 740193a#diff-bfcfcf0d08b5e5c2965394517079c5cfb2b2a11b2e27cf9d08fb07090cd9a4ceR32, meaning mypy is getting confused when you're trying to use it as a variable rather than as a type.

It's my mistake; I can send an alternative PR to fix it :)

[Fokko]

Thanks for the quick response and the background info @AlexWaygood. Feel free to send an alternative PR; you're the expert here :)

[AlexWaygood]

#7634 should fix it, though I haven't tested it. I'm pretty sure the recent switch to using TypeAlias in more places was the cause, though :)