As part of our two-day sprint in July, the khmer project will be offering a mentored open source contributathon. This will provide an opportunity for people interested in trying out the "GitHub flow" model, in which contributions are submitted for review using a pull request. Since the project has lots of unit tests and fairly high code coverage, people can also see how testing and code coverage interact with software development in practice. For more information, please see Titus Brown's blog post.
This post originally appeared in the Software Carpentry blog.