Have the subprocess module set the filename in the FileNotFoundError
exception raised on POSIX systems when the executable or cwd are missing.

bpo-29741: Update some methods in the _pyio module to also accept integer types. Patch by Oren Milman. (#560)

The fix for bpo-23835 fixed ConfigParser behavior in defaults= handling.
Unfortunately, it caused a backwards compatibility regression with
RawConfigParser objects which allow for non-string values.

This commit restores the legacy behavior for RawConfigParser only.

Subclasses such as IndentError and TabError should not have this message
applied.

* Mention how to find out what to do
* Update URL
* Thanks contributors
* Explain there is no timeline

* Don't leak the module into sys.modules
* Avoid dangling thread

* bpo-31249: Fix ref cycle in ThreadPoolExecutor

concurrent.futures: WorkItem.run() used by ThreadPoolExecutor now
breaks a reference cycle between an exception object and the WorkItem
object. ThreadPoolExecutor.shutdown() now also clears its threads
set.

* shutdown() now only clears threads if wait is true.

* Revert changes on shutdown()

PEP 523 introduced _PyEval_EvalFrameDefault which inlines PyEval_EvalFrameEx on
non-debug shared builds.  This breaks the ability to use py-bt, py-up, and
a few other Python-specific gdb integrations.

This patch fixes the problem by only looking for _PyEval_EvalFrameDefault
frames.

test_gdb passes on both a debug and a non-debug build.

Original patch by Bruno "Polaco" Penteado.

Title says all.

* Enforce that configparser defaults are strings
* Update test_configparser.py

bpo-30121: Test the Popen failure when Popen was created with pipes.
Create also NONEXISTING_CMD variable in test_subprocess.py.

* bpo-31238: pydoc ServerThread.stop() now joins itself

ServerThread.stop() now joins itself to wait until
DocServer.serve_until_quit() completes and then explicitly sets
its docserver attribute to None to break a reference cycle.

* Add NEWS.d entry

Add a BaseTestCase class to test_concurrent_futures to check for
dangling threads and processes on all tests, not only tests using
ExecutorMixin.

xmlrpc.server now explicitly breaks reference cycles when using
sys.exc_info() in code handling exceptions.

* bpo-9566: Silence warnings from pyatomic.h macros

Apparently MSVC is too stupid to understand that the alternate branch is
not taken and emits a warning for it.

Warnings added in https://github.com/python/cpython/pull/2383

* bpo-9566: A better fix for the pyatomic.h warning

* bpo-9566: Remove a slash

Part 3 of 3.  Remove old highlight functions and load_config as this functionality is now contained within classes. Patch by Cheryl Sabella.

Patch 2 of 3, to avoid horrendous diff.  Create highlights page from new HighPage class instead of old ConfigDialog methods and change tests to match.

test_bare_raise_in_brand_new_thread() now explicitly breaks a
reference cycle to not leak a dangling thread.

This is the first half of a patch similar to the one for for bpo-31205.  It is being split into 2 PRs to avoid what happened with PR-3096 -- an incomprehensible diff that could not be cleanly backported to 3.6.  This half copies several methods of ConfigDialog and turns them into a new class.

* bpo-30830: test_logging uses threading_setup/cleanup

Replace @support.reap_threads on some methods with
support.threading_setup() in setUp() and support.threading_cleanup()
in tearDown() in BaseTest.

* bpo-30830: test_logging disables threaded socketserver tests

Disable tests because of socketserver.ThreadingMixIn leaks threads,
whereas leaking threads now makes a test to fail on buildbots.

Disable tests until socketserver is fixed: bpo-31233.

* Skip also setup_via_listener()

* bpo-30947: Update libexpat from 2.2.1 to 2.2.3

* Add NEWS entry

* Add new loadlibrary.c

* expat_external.h: restore include "pyexpatns.h"

* PCbuild: add expat/loadlibrary.c

* Define XML_POOR_ENTROPY to compile expat

fork_wait.py tests now joins threads, to not leak running threads in
the background.

bpo-31231, bpo-30871: Replace "./python -m test.pythoninfo" with
"make pythoninfo", since macOS uses ./python.exe.

* bpo-30121: Fix debug assert in subprocess on Windows

This is caused by closing HANDLEs using os.close which is for CRT file
descriptors and not for HANDLEs.

* bpo-30121: Suppress debug assertion in test_subprocess when ran directly

* bpo-30871: pythoninfo: more sys, os, time data

PythonInfo now converts types other than intger to string by default.

* fix typo