Clippy fixes

[ratmice]

The first patch is hand written, so that the subsequent cargo clippy --fix won't introduce compilation errors with the borrow checker.

[ratmice]

Perhaps rather than adding the trait impl, instead I should put more effort into rewriting the code block?

Maybe a match parsed_header block would fix it because it currently errors later when we parsed_header.unwrap(), and when using match the compiler knows both arms are disjoint.

Edit: That will work, but it is a 200+ line Ok(...) block for the rest of the function, which the unwrap was preventing indentation of. However the clippy if let ... && ... has reduced the indentation on the inner block significantly, so it really doesn't too terribly.

I went ahead and pushed that, happy to back it out though...

[ltratt]

I think this is good. Do you want to squash?

[ratmice]

I went ahead and squashed, I'd rather keep the clippy/manual rewrites separate, but it seemed like a pain to do.
(Easier to just rewrite the whole patch if we want to preserve that)

[ltratt]

Hmm, we've hit a now-classic GitHub problem and the only way I know how to resolve it is: can you amend the last commit (e.g. just update the time) and force push? [I wish I knew a better way to fix this...]

[ratmice]

Done.