Increase timeouts from 10 seconds to 1 minute.

bpo-30339, bpo-33913:

* Increase timeout from 10 seconds to 1 minute in
  test_source_main_skipped_in_children source of
  test_multiprocessing_main_handling.
* Replace time.time() with time.monotonic().
* On timeout, include the duration in the error message.

test_mymanager_context() now also accepts -SIGTERM as an expected
exitcode for the manager process. The process is killed with SIGTERM
if it takes longer than 1 second to stop.

OpenProcess() creates a new handle that must be closed later.

Fix a race condition in Popen of
multiprocessing.popen_spawn_win32. The child process now duplicates
the read end of pipe instead of "stealing" it.

Previously, the read end of pipe was "stolen" by the child process,
but it leaked a handle if the child process had been terminated
before it could steal the handle from the parent process.

Tolerate a different of 50 ms, instead of just 30 ms, in
test_timeout() of multiprocessing tests. This change should fix such
test failure on Windows:

FAIL: test_timeout (test.test_multiprocessing_spawn.WithProcessesTestQueue)
Traceback (most recent call last):
  File "lib\test\_test_multiprocessing.py", line 753, in test_timeout
    self.assertGreaterEqual(delta, 0.170)
AssertionError: 0.16138982772827148 not greater than or equal to 0.17

Handle subnormal weights for choices()

Import pyshell first in htest to call SetProcessDpiAwareness on Windows
before tkinter.Tk() is called for the htest. Apparently, 'root.destroy()'
undoes a previous 'root = Tk()'. Since IDLE unittests always destroy roots,
a unittest before an htest does not require anything more to work right.
Since part of the purpose of human-viewed tests is to determine that
widgets look right, it is important that they look the same for testing
as when running IDLE.

it's better to refer to PEP with `pep` role in reStructuredText. It also links to the PEP page.

Fix bug in `Lib/test/libregrtest/runtest.py` that makes running tests an extra time than the specified number of runs.

Add check for invalid --huntrleaks/-R parameters.

These should have been included in PR 7836.

This reverts commit 8fbbdf0c.

Adds references to info about file modes, `time.strftime()`, string formatting
syntaxes, and logging levels.

This avoids a failure in at least one case when running only a single
test method rather than all tests in the module.

The issue came up when testing the following on Windows 10 Pro 64-bit:
HighPageTest.test_highlight_target_text_mouse

Directly executed pyc files were being kept open longer than necessary.

(cherry picked from commit c45cb479074b5d25f0d382d3109f527520a9f03c)
Co-authored-by: Andrés Delfino <adelfino@gmail.com>

In configdialog, the custom tabbedpages widget was replaced
by ttk.notebook several months ago.

bz2, lzma: When Decompressor.__init__() is called twice, free the old
lock to not leak memory.

The statement is true for Windows (and macOS) also.

* Add support.MS_WINDOWS: True if Python is running on Microsoft Windows.
* Add support.MACOS: True if Python is running on Apple macOS.
* Replace support.is_android with support.ANDROID
* Replace support.is_jython with support.JYTHON
* Cleanup code to initialize unix_shell

Calling Py_Initialize() twice does nothing, instead of failing with a
fatal error: restore the Python 3.6 behaviour.

Increases coverage by 44%.

Add missing warning filter to test_exec_filename().

Increase the timeout from 1 min to 5 min.

Replace also time.time() with time.monotonic() for timeouts.