We need an older version of Ruby to run this example. We can install it 
using `rbenv`, which is similar to Python's virtual environments.

Set up the environment:
  * sudo apt update
  * sudo apt install git curl autoconf bison build-essential libssl-dev libyaml-dev libreadline6-dev zlib1g-dev libncurses5-dev libffi-dev libgdbm6 libgdbm-dev libdb-dev
  * curl -fsSL https://github.com/rbenv/rbenv-installer/raw/HEAD/bin/rbenv-installer | bash
  * echo 'export PATH="$HOME/.rbenv/bin:$PATH"' >> ~/.bashrc
  * echo 'eval "$(rbenv init -)"' >> ~/.bashrc
  * source ~/.bashrc
  * rbenv install 2.7.8
  * rbenv global 2.7.8

github_url: https://github.com/floere/phony
good_tag: v1.9.0
bad_tag: v2.10.0
test_command: ruby -e 'require "./lib/phony"; Phony.normalize("999")'

We will use `git bisect` to find the commit where the failure begins.

Useful commands:

git bisect start: start a bisecting search
git bisect good: mark a commit as "good"
git bisect bad: mark a commit as "bad"
git bisect reset: get out of a bisecting search
git bisect run: run a script to automate the search (needs a good and bad mark)