Comment 1 for bug 476418

This is ready for review in the attached branch. For now I've decided to leak a bit the implementation of MockerTestCase by calling its private __cleanup method in run_isolated, because it makes the fix very simple and isolated.

So if you look at your /tmp after the test suite has run you'll notice that from the hundreds of files we had before we're down to only one, which is a pipe, probably left open by some script execution test. I'll have to investigate that further.