Finding what branch a Git commit came from

Question

Is there a way to find out what branch a commit comes from given its SHA-1 hash value?

Bonus points if you can tell me how to accomplish this using Ruby Grit.

Answer 1

As an experiment, I made a post-commit hook that stores information about the currently checked out branch in the commit metadata. I also slightly modified gitk to show that information.

You can check it out here: https://github.com/pajp/branch-info-commits