Pull Requests are great for understanding the larger thinking around a change or set of changes made to a repo. Reading pull requests are a great way to quickly \"grok\" a p
I had this same problem and wrote the pr_for_sha bash helper, documented here:
http://joey.aghion.com/find-the-github-pull-request-for-a-commit/
Call it like pr_for_sha and it will open the corresponding github pull request page in a browser.
pr_for_sha