Since introduction of Developer's Certificate of Origin in phpMyAdmin, we've struggled with automatically checking pull requests on GitHub that they match this.
First attempt was to integrate this check into Travis environment, but that proven to be hard to understand by potential contributors as it did not give direct feedback what went wrong. So it was still useful for us, but still we had to explain the situation. With recent flood of contributions from potential GSoC students, it became quite tedious task.
So let's automate that. GitHub has quite powerful API, so it should not be that hard. Looking at Webhooks documentation, it is quite easy to get hooked on pull request creation and updates and checking commits and adding comments is just a piece of cake. The hardest choice was choosing language in which to implement it :-). While not finding binding for GitHub in any of my favorite language packaged in Debian. I've decided to hack this quickly in PHP without using any library and if this turns out to be limitation in future, it can be easily rewritten.
First incarnation of our commit checker did check just Signed-Off-By lines in commit messages, but I've found that there might be some other useful checks. So the script got extended for various simple coding style violations, which we see quite often like wrong indentation or using DOS end of lines (the example of all fired checks can be found in pull request 1081). You can find the code for it in our scripts repository.
