I have been asked to write a script that pulls the latest code from Git, makes a build, and performs some automated unit tests.
I found that there are two built-in Python modules for interacting with Git that are readily available: GitPython and libgit2.
What approach/module should I use?
If GitPython package doesn't work for you there are also the PyGit and Dulwich packages. These can be easily installed through pip. 
But, I have personally just used the subprocess calls. Works perfect for what I needed, which was just basic git calls. For something more advanced, I'd recommend a git package.
Use Git commands within Python code