Install old formula versions with homebrew

using-brew-versions.sh

~$ cd $(brew --prefix)

/usr/local$ brew versions openssl
Warning: brew-versions is unsupported and may be removed soon.
Please use the homebrew-versions tap instead:
  https://github.com/Homebrew/homebrew-versions
1.0.1h   git checkout 7541601 Library/Formula/openssl.rb
1.0.1g   git checkout db3123d Library/Formula/openssl.rb
1.0.1f   git checkout 0b515fb Library/Formula/openssl.rb
1.0.1e   git checkout 3c62281 Library/Formula/openssl.rb
1.0.1d   git checkout c44c37a Library/Formula/openssl.rb
1.0.1c   git checkout 31df36e Library/Formula/openssl.rb
1.0.1a   git checkout 18855a3 Library/Formula/openssl.rb
1.0.1    git checkout 768e5a3 Library/Formula/openssl.rb
0.9.8s   git checkout a2e8b54 Library/Formula/openssl.rb
0.9.8r   git checkout 0ea7351 Library/Formula/openssl.rb
0.9.8o   git checkout 83ed494 Library/Formula/openssl.rb

/usr/local$ git checkout 768e5a3 Library/Formula/openssl.rb

/usr/local$ brew install openssl
==> Downloading http://www.openssl.org/source/openssl-1.0.1.tar.gz
######################################################################## 100.0%
==> perl ./Configure --prefix=/usr/local/Cellar/openssl/1.0.1 --openssldir=/usr/local/etc/openssl zlib-dynamic shared darwin64-x86_64-c
==> make
==> make test
==> make install MANDIR=/usr/local/Cellar/openssl/1.0.1/share/man MANSUFFIX=ssl
This formula is keg-only, so it was not symlinked into /usr/local.
...
==> Summary
🍺  /usr/local/Cellar/openssl/1.0.1: 429 files, 14M, built in 3.6 minutes

$ git checkout Library/Formula/openssl.rb