Note that the test.* namespace has long been declared as unstable, so we
don't worry about breaking third party code when rearranging the test suite
(as far as I am aware, most Linux distros don't even include the test suite
in their Python packages).

I'll see how Mercurial goes tracking the file move when the alias is left
behind, and decide which way to do the initial change based on whether or
not the alias breaks the history tracking.