New Test Nagger

#1

You’re going to start seeing the following panel show up in GitHub PRs on the Istio repo:

This is an experiment. It’s intended to remind you that changes in the product to fix a bug should usually be accompanied by an update to tests.

This won’t block checkins, it’s just advisory. Code reviewers should keep an eye out too and not allow fixes without corresponding test updates.

The heuristic the bot uses is pretty simple. It looks for the word “Fix” in the body, and then tries to find a file with the word “test” in the name. Let me know if this ends up triggering a lot of incorrect results and we can tweak it easily.