Issue #19595: Re-enable a long-disabled test in test_winsound
Issue #19698: Remove exec_module() from the built-in and extension
module loaders.

Due to the fact that the call signatures for extension modules and
built-in modules does not allow for the specifying of what module to
initialize and that on Windows all extension modules are built-in
modules, work to clean up built-in and extension module initialization
will have to wait until Python 3.5. Because of this the semantics of
exec_module() would be incorrect, so removing the methods for now is
the best option; load_module() is still used as a fallback by
importlib and so this won't affect semantics.
asyncio: Add 'shield' to __all__.
Set the FDs non-blocking in the selectors example.
Remove trailing blanks.
Issue #19712: Port test.test_importlib.import_ tests to use PEP 451
that don't require changing test.test_importlib.util.mock_modules().
Revert unrelated changes introduced by changeset b2066bc8cab9  (issue #19795).
Null merge
More realistic example for selectors.py.
Null merge
Issue #3693: Fix array obscure error message when given a str.
Fix and test pip version consistency