Broken links: Opam archive URLs pointing to GitHub

I have noticed that in some of our Opam packages that point to GitHub the archive links are no longer working:

Unless this is temporary, this has the potential to affect a lot of Opam packages.

I have used this sed(1) command to fix url files:

sed -i -e 's!^\(.*github.com/.*/archive\)/\([^/]*\)/.*"!\1/\2.tar.gz"!' url

Maybe this was a temporary glitch on GitHub’s side. The old link works again.