Describe the Bug

Pyrefly reports bad-override when subclassing str and overriding upper with an additional optional argument. Pyright accepts this code.

class MyString(str):
    def upper(self, locale: str = "en") -> str:
        return super().upper()

This seems like another override compatibility false positive in method signature checking for built-in subclasses.

Sandbox Link (Pyrefly)

https://pyrefly.org/sandbox/?project=N4IgZglgNgpgziAXAAlHAhgOwCYCMD2AHgHQAOAnksiAMZTpxzICy5AygC4BOEmA5gAo43AJSIAOpmTTk2GGGQBXUqRhchMKGAA0yKPhrpYKYV2QBeZOJAxM1kcgC0APmSmJUmV64wOirlJwymoCIsTKquoiIAC%2BuiDoNBwQAG4wAGLQMFQgGDgEJBSxQA

Reference (Pyright)

https://pyright-play.net/?code=MYGwhgzhAECyCeBlALgJwJYDsDmAKCaAlAFwBQ0F0AJgKYBm0ArgA7M2r40h0A00IAe2BgQNYtAKpoAXmgAiGpjmFoAWgB8EtGUq7oqGskapMElu1yEAdCzYdCQA

Sandbox Link

No response

(Only applicable for extension issues) IDE Information

No response