For a vanishingly small number of internal types, CPython sets the
tp_name slot to mod_name.type_name, either in the PyTypeObject or the
PyType_Spec. There are a few minor places where this surfaces:

* Custom repr functions for those types (some of which ignore the
  tp_name in favor of using a string literal, such as _io.TextIOWrapper)
* Pickling error messages

The existing test suite only tests the former.

This makes it tricky for other Python implementations to pass the test suite if
they do not expose the module name (_io, _ssl, _tkinter, etc) in their type
names.