If you want more information on this specific change you can look at the revision that implements it or simply inspect the corresponding patch file. By the way, some of the tests already fail! That's because they were not run often enough in the past, something that ATF is supposed to resolve.
While waiting for a NetBSD release build to complete, I have started working on a real web site for ATF. Don't know if I'll keep working on it now because it's a tough job and there is still a lot of coding to do. Really! But, on the other hand, having a nice project page is very good marketing.