To keep this PR manageable, I'm going to fix any issues in CI by just reverting the affected functions.

Notes on CI:

• stubtest failure because stubtest doesn't see a str as compatible with a TypeVar(bound=str) in urllib.parse
• urllib.parse.urlencode also has a default of None where our type is str, needs investigation; same for sysconfig.is_python_build, platform.libc_ver, ssl._create_unverified_context
• and shutil.make_archive but with 0 vs. False; same for platform.platform, distutils.util.execute, distutils.util.byte_compile, distutils.spawn, and a bunch of others
• flake8-pyi seems to think string defaults are annotations, so it will need a fix

We also got a pytype crash

Traceback (most recent call last):
  File "/opt/hostedtoolcache/Python/3.10.9/x64/lib/python3.10/site-packages/pytype/pyi/visitor.py", line 36, in _call_visitor
    return super()._call_visitor(node)
  File "/opt/hostedtoolcache/Python/3.10.9/x64/lib/python3.10/site-packages/pytype/ast/visitor.py", line 55, in _call_visitor
    return visitor(node)
  File "/opt/hostedtoolcache/Python/3.10.9/x64/lib/python3.10/site-packages/pytype/pyi/parser.py", line [16](https://github.com/python/typeshed/actions/runs/3896137144/jobs/6652302058#step:7:17)2, in visit_Pyval
    return self.convert_late_annotation(node.value)
  File "/opt/hostedtoolcache/Python/3.10.9/x64/lib/python3.10/site-packages/pytype/pyi/parser.py", line 142, in convert_late_annotation
    typ = a.body[0].value  # pytype: disable=attribute-error
IndexError: list index out of range

I suspect like flake8-pyi it's something to do with treating string defaults as annotations but I'll have to look at the code.

Just checking, you ran latest stubtest locally with the default checking you added?

Not yet, I forgot it hadn't been released yet.

We've often used pre-release stubtest in CI. Might be a good idea to do that now too!

For reference fdc5863 is where we undid stubtest-from-master most recently, but some of the infra has changed since then so it's not just a matter of reverting and updating the commit.

New version with the latest stubdefaulter:

• Now only adds defaults for 3.11 branches
• Now also adds defaults to methods
• Undid a bunch of things stubtest complained about

The PR currently doesn't include a change to the version of stubtest. If we want to run stubtest from mypy master, I'd rather do that in a separate PR.

According to mypy_primer, this change has no effect on the checked open source code. 🤖🎉