Fuschia builds are going to block beta backports

[aidanhs]

In #41365 we saw a travis failure because a URL was not a valid gz - https://travis-ci.org/rust-lang/rust/jobs/223417092#L991.

https://fuchsia.googlesource.com/third_party/llvm/+archive/5463083.tar.gz seems dead.

While the docker image is reused from the cache we can get by, but this is probably going to start blocking the queue shortly (I'm not currently clear what caused the linked PR to do the rebuild).

ping @tedsta @raphlinus

[aidanhs]

Ah, looks like it's because this was a PR to beta. So #41130 needs backporting as well (or the url needs restoring) or beta backports are going to be blocked, ping @petrhosek

[petrhosek]

Would it be possible to backport #41130?

[aidanhs]

Yeah that's what we're going to try in #41397

[frewsxcv]

Presumably resolved in #41397