Weird stuff in a cfe-commits message from github

If you look at this in the cfe-commits archive
https://lists.llvm.org/pipermail/cfe-commits/Week-of-Mon-20220523/419625.html
it has some funky HTML in it (see “Hello future GitHubber!” etc)
I don’t see this in the commit messages before or after this one.

So… what’s with that?

It’s a github page saying:

No server is currently available to service your request.
Sorry about that. Please try refreshing and contact us if the problem persists.

Plus a picture of a unicorn.

I guess the mailer got this response instead of the diff that normally goes in the email.