Publish `bz2` archives for macOS builds on `downloads.haskell.org`
Motivation
Stack users are currently facing severe slowdowns when setting up Haskell projects, due to Stack retrieving GHC from a non-CDN location (stack#2240). To fix that, Linux and Windows builds will soon be fetched from downloads.haskell.org (stackage-content#82). Unfortunately, it's not yet possible to do the same for macOS as it cannot extract .xz archives out-of-the-box which is the only format offered on downloads.haskell.org. macOS users will therefore still experience slowdowns.
Proposal
It would be nice if .bz2 archives would be published for macOS builds too.
I suspect this would be a pretty simple change somewhere, but I haven't found the relevant files yet. If someone could point me in the right direction that would be great.
Older archives
I've repackaged all published macOS builds here. The archive all.tar contains all tar.bz2 archives in a single file. To recreate this locally:
#!/bin/bash
cat <<EOF > files
https://downloads.haskell.org/~ghc/7.8.4/ghc-7.8.4-x86_64-apple-darwin.tar.xz
https://downloads.haskell.org/~ghc/7.10.1/ghc-7.10.1-x86_64-apple-darwin.tar.xz
https://downloads.haskell.org/~ghc/7.10.2/ghc-7.10.2-x86_64-apple-darwin.tar.xz
https://downloads.haskell.org/~ghc/7.10.3/ghc-7.10.3b-x86_64-apple-darwin.tar.xz
https://downloads.haskell.org/~ghc/8.0.1/ghc-8.0.1-x86_64-apple-darwin.tar.xz
https://downloads.haskell.org/~ghc/8.0.2/ghc-8.0.2-x86_64-apple-darwin.tar.xz
https://downloads.haskell.org/~ghc/8.2.1/ghc-8.2.1-x86_64-apple-darwin.tar.xz
https://downloads.haskell.org/~ghc/8.2.2/ghc-8.2.2-x86_64-apple-darwin.tar.xz
https://downloads.haskell.org/~ghc/8.4.1/ghc-8.4.1-x86_64-apple-darwin.tar.xz
https://downloads.haskell.org/~ghc/8.4.2/ghc-8.4.2-x86_64-apple-darwin.tar.xz
https://downloads.haskell.org/~ghc/8.4.3/ghc-8.4.3-x86_64-apple-darwin.tar.xz
https://downloads.haskell.org/~ghc/8.4.4/ghc-8.4.4-x86_64-apple-darwin.tar.xz
https://downloads.haskell.org/~ghc/8.6.1/ghc-8.6.1-x86_64-apple-darwin.tar.xz
https://downloads.haskell.org/~ghc/8.6.2/ghc-8.6.2-x86_64-apple-darwin.tar.xz
https://downloads.haskell.org/~ghc/8.6.3/ghc-8.6.3-x86_64-apple-darwin.tar.xz
https://downloads.haskell.org/~ghc/8.6.4/ghc-8.6.4-x86_64-apple-darwin.tar.xz
https://downloads.haskell.org/~ghc/8.6.5/ghc-8.6.5-x86_64-apple-darwin.tar.xz
https://downloads.haskell.org/~ghc/8.8.1/ghc-8.8.1-x86_64-apple-darwin.tar.xz
https://downloads.haskell.org/~ghc/8.8.2/ghc-8.8.2-x86_64-apple-darwin.tar.xz
https://downloads.haskell.org/~ghc/8.8.3/ghc-8.8.3-x86_64-apple-darwin.tar.xz
https://downloads.haskell.org/~ghc/8.8.4/ghc-8.8.4-x86_64-apple-darwin.tar.xz
https://downloads.haskell.org/~ghc/8.10.1/ghc-8.10.1-x86_64-apple-darwin.tar.xz
https://downloads.haskell.org/~ghc/8.10.2/ghc-8.10.2-x86_64-apple-darwin.tar.xz
https://downloads.haskell.org/~ghc/8.10.3/ghc-8.10.3-x86_64-apple-darwin.tar.xz
EOF
wget -i files
rm files
unxz *.xz
ls *.tar | parallel -I% --max-args 1 bzip2 -9 %