typing: add a cast to `mercurial.patch` to unconfuse pytype 2024.10.11 I've seen this in other, more modern versions of pytype than what we use in CI- it thinks the return of `get_payload()` is `Message | bytes`, and then complains about `if not payload.endswith(b'\n')` below, saying `Message` doesn't have that function. That's correct, but according to the table in `get_payload()` that documents what the method returns, the only possible values are `bytes | None` when `decode=True` and the `i` argument isn't passed. And `None` isn't possible if we trust the `Content-Type` header. While here, I added a type hint for the `part` variable, since PyCharm couldn't figure out what was going on here, and that made navigating to the code impossible.