Should we check the diffs whenever new code is committed?

In servo/servo#11267, the author modified the stuff inside python, and I was notified by highfive when the PR was opened. Later, new commits were added, where the author went for modifying the CI scripts (whose watcher is @aneeshusa). Wouldn't it be better if he got notified by it?

I suggest we should check the diff whenever new code is committed. We should probably store the state of the notified watchers somehow and check it before notifying someone again (so that we don't thrash the PR with comments!).

Whenever I think of a new suggestion, I'm worried about #124. Then, there's the problem of feasibility. Can we actually do this?

[jdm]

I'm generally favourable towards this, but I worry that we'll end up getting the same notifications over and over in the common case (such as modifying unsafe code and going through several rounds of review).

[metajack]

A good heuristic might be to rescan new diffs, but stop doing scanning after rebases.