307 Temporary Redirect not followed for HEAD request

[pkgw]

The tectonic TeX engine uses reqwest to fetch information about TeX support files, starting with a HEAD request to https://archive.org/services/purl/net/pkgwpub/tectonic-default. The Internet Archive recently changed their service to reply to this service with a 307 HTTP code instead of 302, and that breaks Tectonic:

note: connecting to https://archive.org/services/purl/net/pkgwpub/tectonic-default
error: unexpected HTTP response code 307 Temporary Redirect for URL https://archive.org/services/purl/net/pkgwpub/tectonic-default

If I'm understanding the design of the standards and reqwest correctly, reqwest ought to follow this redirect. I think that the relevant logic is:

            let should_redirect = match res.status() {
                StatusCode::MOVED_PERMANENTLY | StatusCode::FOUND | StatusCode::SEE_OTHER => { ... }
                StatusCode::TEMPORARY_REDIRECT | StatusCode::PERMANENT_REDIRECT => {
                    match self.body {
                        Some(Some(_)) | None => true,
                        Some(None) => false,
                    }
                }
                _ => false,
            };

Unfortunately I don't know what the double-option structure of self.body means so it's hard for me to understand what's going on here.

I need to stop using archive.org anyway because it's blocked in China, so this issue is getting me to finally do that —which means that even though this breaks Tectonic in a mission-critical way it's not urgent. But I do think there's a misbehavior in reqwest here.

[pkgw]

Sorry, this was my mistake. reqwest is doing the right thing here. Our redirection logic just doesn't properly follow the attempt due to a limitation in our logic.