Remove regression test for Distribute issue #318. The continuing relevance of this test is questionnaible, given that user installs of setuptools no longer imply user installs of other packages. Ref #360.

Remove comment that references a setup command, but even at the time it was committed, it's not duplicate code from anything in setuptools, and I'm unaware of what a setup command is.

Fix tox settings so they work

It seems like if it has an `__eq__` method, it should probably have a `__ne__` method.

I ran into this while working on pip -- see https://github.com/pypa/pip/pull/2493#discussion_r25955295