Fixed module blacklist to exclude installing test modules rather than "tests" modules

Portage, in its [non-ironically] infinite wisdom (or at least, very great) refused to install the latest version since it attempts to install the test module.

I should have looked more closely before copying the example blacklist from the setuptools documentation, as while it does do what we want, we have test and test/testrepo modules that need to be excluded, neither of which start with tests.