With CodeIgniter moving to GitHub we are starting to see a lot of CodeIgniter developers wanting to learn more about Git, specifically how they can use it to improve their workflows, manage their applications and move away from the horrible days of copying and pasting updated libraries off a wiki. UCK. Sparks are helping us on the whole, but there is another method that we can use to manage our packages: Git Submodules.
Submodules allow you to pull in source from a remote repository without having to merge the code into your own. It creates a dependency between the two and makes it easier to check out only what you need. He gives the example of his oauth2 package being needed in multiple other applications, so instead of including and checking in multiple versions, he made a separate repo and defined the source as a submodule. He also includes a bit about fixing issues in your submodules with a few handy commands to get on the right branch, add a remote and push the commit.