As a scientist, you know the importance of a lab notebook. A version control system achieves the same for programmers.
Questions you can ask include:
- Is there a repository with the latest version of all code?
- Are files kept there as well?
- Are there multiple branches?
- Do you know what the branches have been used for?
- Are past releases tagged in the repository?
Starting with a version control system in place from the very beginning will save you a lot of pain. All version control systems (SVN, Mercurial, git, etc.) allow you to check the first criterion: