* Improve signal delivery

Avoid using Py_AddPendingCall from signal handler, to avoid calling signal-unsafe functions.

* Remove unused function

* Improve comments

* Use _Py_atomic API for concurrency-sensitive signal state

* Add blurb

Updates ssl and tkinter projects to use pre-built externals

* Add section to idlelib/idle-test/README.txt.
* Include check that branches are taken both ways.
* Exclude IDLE-specific code that does not run during unit tests.

AIX uses iso8859-1 in the C locale, not ASCII

AIX doesn't currently provide any of the locale
coercion locales, but we leave locale coercion
enabled in case one gets added in the future.

The will help writing dialog improvements and splitting the class into multiple classes.
Original patch by Cheryl Sabella.

Initial patch by Louie Lu.

bpo-30731: python.manifest fix

encoder and decoder.

when pass bad strict argument.

Changed "subbset" to "subset". Also made the sentences read like things were happening instead of stating what the code should do (in other words more descriptive than prescriptive).

Patch by Louie Lu.

tearDown() now clears explicitly the self.server variable to make
sure that the thread is completely cleared when tearDownClass()
checks if all threads have been cleaned up.

Fix the following warning:

$ ./python -m test --fail-env-changed -m test.test_os.TestSendfile.test_keywords -R 3:1 test_os
(...)
Warning -- threading_cleanup() failed to cleanup 0 threads after 3 sec (count: 0, dangling: 2)
(...)
Tests result: ENV CHANGED

instead of failing with SystemError.

Relative import from non-package now fails with ImportError rather than
SystemError.

Also improve test of config.ConfigChanges.delete_section.
Original patch by Cheryl Sabella.

Patch by Cheryl Sabella.

Based on patch by Victor Stinner.

called with bytes-like argument.

* Rewrite importlib _get_module_lock(): it is now responsible to hold
  the imp lock directly.
* _find_and_load() now holds the module lock to check if name is in
  sys.modules to prevent a race condition

Handle getattr(copy, 'deepcopy') error in _elementtree module
initialization.

One is a duplicate, one is set but cannot be altered by users.
Patch by Cheryl Sabella.

multiprocessing.Queue.join_thread() now waits until the thread
completes, even if the thread was started by the same process which
created the queue.

Fix the following warning which occurs randomly when running
test_handle_called_with_mp_queue of test_logging.QueueListenerTest:

Warning -- threading_cleanup() failed to cleanup -1 threads after 4 sec (count: 0, dangling: 1)

Patch by Louie Lu.

to staticmethod() and classmethod().

Turns out that history-size was added in readline 6.0. This explain why
this tests fail on FreeBSD when using readline 5.2. We skip now the
history size if readline does not support it.

See https://cnswww.cns.cwru.edu/php/chet/readline/CHANGES for
details.

* In config, put dump test code in a function; run it and unittest in 'if __name__ == '__main__'.
* Add class config.ConfigChanges based on changes_class_v4.py on bpo issue.
* Add class test_config.ChangesTest, partly based on configdialog_tests_v1.py on bpo issue.
* Revise configdialog to use ConfigChanges, mostly as specified in tracker msg297804.
* Revise test_configdialog to match configdialog changes.  All tests pass in both files.
* Remove configdialog functions unused or moved to ConfigChanges.
Cheryl Sabella contributed parts of the patch.

* test_readline logs the versions of libreadline when run in verbose
  mode
* Add also readline._READLINE_LIBRARY_VERSION

If history-length is set in .inputrc, and the history file is double the
history size (or more), history_get(N) returns NULL, and python
segfaults. Fix that by checking for NULL return value.

It seems that the root cause is incorrect handling of bigger history in
readline, but Python should not segfault even if readline returns
unexpected value.

This issue affects only GNU readline. When using libedit emulation
system history size option does not work.