Comment handler not serving u-in-reply-to for reply that's also @-mention

[snarfed]

Originally posted by @snarfed in https://github.com/aaronpk/webmention.io/issues/187#issuecomment-1819754100:

Not entirely sure what's going on here, but I suspect the problem is we're finding that post at least two different ways, as a downstream reply and as an @-mention, and we're not merging the two versions. Eg we sent this webmention for the reply, but when webmention.io fetches the source page, we render it as the @-mention, so it doesn't have u-in-reply-to pointing to https://joshuawood.net/webmentions .

I thought we fixed this a long time ago, in https://github.com/snarfed/bridgy/issues/533 and snarfed/bridgy@a10a5a1c37c6419717d940a6dee7401462975ac9, but maybe not, or maybe not all variations. Will look. I suspect this one is tricky though, no promises.

[snarfed]

Original report from @joshuap in https://github.com/aaronpk/webmention.io/issues/187#issuecomment-1818189503 :

{
  "status": "no_link_found",
  "source": "https://brid.gy/comment/mastodon/@wood@hachyderm.io/111439777418267489/111439855894516928",
  "target": "https://joshuawood.net/webmentions",
  "summary": "The Microformats at the source URL do not contain a link to the target URL. Check the source URL in a Microformats parser such as php.microformats.io"
}

It's strange because it accepted the reply that this was in response to, but it won't accept this one. I check the microformats on php.microformats.io as suggested, and it parsed the source URL just fine afaict:

http://php.microformats.io/?url=https%3A%2F%2Fbrid.gy%2Fcomment%2Fmastodon%2F%40wood%40hachyderm.io%2F111439777418267489%2F111439855894516928

[snarfed]

https://github.com/pfefferle/wordpress-webmention/issues/454#issuecomment-1879203227 may be an instance of this without an @-mention. @jaschaurbach posted a top-level post, then a reply to a reply, and then someone else's reply to that is similarly missing the u-in-reply-to to the top-level post's original post.

The root problem here, or at least one, is that https://brid.gy/comment/mastodon/@jascha@ohai.social/111681444048580159/111681453109020359 should have u-in-reply-to link pointing to https://jascha.wtf/angels-at-chaos-about-volunteering-and-fitting-in/ , but doesn't.

That post is both a direct reply to https://chaos.social/@jascha@ohai.social/111681444071267594 and an indirect reply to the root post https://chaos.social/@jascha@ohai.social/111679915834398325 . The original post https://jascha.wtf/angels-at-chaos-about-volunteering-and-fitting-in/ is in the latter. Bridgy should still find it, but my guess is that the immediate parent is overriding it somehow.