What problem are you trying to solve? I gather you're just plowing through the output of 'make test', looking at each bit of noise, and trying to figure out a way to improve the tests?
While that's a noble quest, and I'd like to encourage people to improve the tests, it might be more productive to do so around areas of pain for users.
For instance, you could look at bugs in bugzilla that have patches attached that aren't committed yet because tests are needed, and write those tests. - Dan