gh-106135: Improve test_patma with more cases

[sobolevn]

I've covered all bullet list items for my original issue.
Do you have some extra test ideas? :)

• Issue: Add more cases to test_patma #106135

[brandtbucher]

Looks great, thanks!

You gave me an idea for another test, but no pressure to add it. I'll give you some time just in case you want to, and merge in a day or two regardless:

[brandtbucher]

If you want to be really crazy, you could add another test with something like this:

x = []
match x:
    case [] as z if z.append(None):
        y = 0
    case [None]:
        y = 1
self.assertEqual(x, [None])
self.assertEqual(y, 1)
self.assertIs(z, x)

[sobolevn]

Done! 👍