Issue 20317: Remove debugging code from contextlib

- Alex J Burke noticed a debugging raise in the commit that
  fixed the original bug reported in issue 20317
- this showed that multiple iterations through the affected
  loop wasn't actually being tested
Merge removal of issue 20317 debugging code from 3.3
Issue #20189: Four additional builtin types (PyTypeObject,
PyMethodDescr_Type, _PyMethodWrapper_Type, and PyWrapperDescr_Type)
have been modified to provide introspection information for builtins.
Also: many additional Lib, test suite, and Argument Clinic fixes.
asyncio: mention that transports/protocols are low-level, streams are high-level
asyncio doc: add a "Coroutines and protocols" section
new plan: just remove typecasts (closes #20374)
merge 3.3 (#20374)
asyncio doc: move AbstractServer to the event loop page

Add also entries in the table of content for each synchronization primitive
class.
asyncio doc: document StreamWriter.drain()
Issue #20384: Fix the test_tarfile test on Windows.

On Windows os.open() error message doesn't contain file name.
Null merge
Fix typo.
Null merge
Issue #20381: Fix sanity checking on default arguments when c_default is
also specified.
update hosting faq
merge 3.3