Virtualenv is nice, but lately I've grown to use docker containers instead. You can use the official containers for go, python or ruby, feed it the gemfile or requirements.txt or whether, tag it, push it and you have a permanent snapshoted image.
It's definitely a hack, but for development environments it's quite an effective one. Which is why we actually created a (more user friendly) clone for Go development. It's called Virtualgo, and it's mentioned near the end of the article as well. https://github.com/GetStream/vg
