Read from data socket to avoid "[SSL] shutdown while in init" exception
during shutdown of the dummy server.
Signed-off-by: Christian Heimes <christian@python.org>

<!-- issue-number: [bpo-34391](https://www.bugs.python.org/issue34391) -->
https://bugs.python.org/issue34391
<!-- /issue-number -->.
(cherry picked from commit 1590c393)
Co-authored-by: Christian Heimes <christian@python.org>

Avoid undefined pointer arithmetic with NULL.
(cherry picked from commit 7c4ab2af)
Co-authored-by: Zackery Spytz <zspytz@gmail.com>

Downstream vendors have started to deprecate weak keys. Update all RSA keys
and DH params to use at least 2048 bits.

Finite field DH param file use RFC 7919 values, generated with

    certtool --get-dh-params --sec-param=high

Signed-off-by: Christian Heimes <christian@python.org>.
(cherry picked from commit 88bfd0bc)
Co-authored-by: Christian Heimes <christian@python.org>

(cherry picked from commit 8f7bb100)

This was backported by mistake in ef19fd20.

The change in the mini language floating point and decimal table
is consistent with 'Exponential notation' and clarifies that we
are referring to the output notation, not an object type.

(cherry picked from commit 28c7f8c8)

(cherry picked from commit 2ebd3813)
Co-authored-by: INADA Naoki <methane@users.noreply.github.com>

Some MacOS-tk combinations need .update_idletasks().
The call is both unneeded and innocuous on Linux and Windows.
Patch by Kevin Walzer.

(cherry picked from commit 9beaef62)
Co-authored-by: Terry Jan Reedy <tjreedy@udel.edu>

* Fix compilation warning in _ctypes module on Window

(cherry picked from commit 20f11fe4)

* Fix compilation warnings on Windows 64-bit

(cherry picked from commit 725e4212)

* Fix compiler warning in unicodeobject.c

Explicitly case to Py_UNICODE to fix the warning:

Objects\unicodeobject.c(4225): warning C4244: '=' :
conversion from 'long' to 'Py_UNICODE', possible loss of data

The downcast cannot overflow since we check that value <= 0x10ffff.

Use a local scope for the 'i' variable.

Fixed bpo-29565: Corrected ctypes passing of large structs by value.

Added code and test to check that when a structure passed by value
is large enough to need to be passed by reference, a copy of the
original structure is passed. The callee updates the passed-in value,
and the test verifies that the caller's copy is unchanged. A similar
change was also added to the test added for bpo-20160 (that test was
passing, but the changes should guard against regressions).

(cherry picked from commit a86339b8)

Added missing .grab_release() calls to all places where we call .grab_set().

(cherry picked from commit 10ea9409)

(cherry picked from commit c48e26dc)
Co-authored-by: INADA Naoki <methane@users.noreply.github.com>

(cherry picked from commit 6921ef7b)
Co-authored-by: Andrés Delfino <adelfino@gmail.com>

bpo-34229: Check start and stop of slice object to be long when they are not int in PySlice_GetIndices (GH-8480)

(cherry picked from commit c0f0a766)
Co-authored-by: Aaron Ang <aaronang@users.noreply.github.com>

The script will exit with the number 0 (zero), instead of the letter O.
(cherry picked from commit 95d34c2a)
Co-authored-by: Mariatta <Mariatta@users.noreply.github.com>

(cherry picked from commit bde782bb)
Co-authored-by: Matthias Bussonnier <bussonniermatthias@gmail.com>

imaplib now allows MOVE command in IMAP4.uid() (RFC 6851:
IMAP MOVE Extension) and potentially as a name of supported
method of IMAP4 object.
(cherry picked from commit caa331d4)
Co-authored-by: Matěj Cepl <mcepl@cepl.eu>

(cherry picked from commit e271ca78)
(cherry picked from commit c75c1e0e)

There was a missing check for integer overflow, several function calls
were not checked for failure, and allocated memory was not freed if an
error occurred.

(cherry picked from commit b12112b5)

(cherry picked from commit feabae96)
Co-authored-by: Raymond Hettinger <rhettinger@users.noreply.github.com>

[2.7] bpo-34068: iobase_close could call PyObject_SetAttrString with an exception set (GH-8282). (GH-8312) (GH-8314)

(cherry picked from commit 28f07364)

Co-authored-by: Zackery Spytz <zspytz@gmail.com>.
(cherry picked from commit cc13016658a9ed86d0b702ab6c251ad5952a952f)

(cherry picked from commit 993030aa)
Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>

(cherry picked from commit 504373c5)

Also backport tests for skipitem() and handling errors.

Actually just one fix on the 2.7 branch.

Contributed by Bradley Laney.

(cherry picked from commit 6b490b5d)

(cherry picked from commit 7762e4d3)
Co-authored-by: Benjamin Peterson <benjamin@python.org>

(cherry picked from commit d6d44327)
Co-authored-by: Benjamin Peterson <benjamin@python.org>

Fixed also testing the "always" warning filter.
(cherry picked from commit b796e7dc)
Co-authored-by: Sergey Fedoseev <fedoseev.sergey@gmail.com>

(cherry picked from commit 2a9b8bab).
(cherry picked from commit 7c43b801503c802ed6ea4b811f5bc73791249d94)

Make the change where discussing the CPython implementation of lists and dicts.
(cherry picked from commit 8d412780)
Co-authored-by: Andrés Delfino <adelfino@gmail.com>

(cherry picked from commit 9c5ba097)
Co-authored-by: Marcin Niemira <marcin@niemira.net>

[2.7] bpo-33804: Document that the argument for io.TextIOBase.read() is optional (GH-7510). (GH-8171)

(cherry picked from commit b6bb77c2)
Co-authored-by: Andrés Delfino <adelfino@gmail.com>

The Opera Browser was using a outdated command line invocation that resulted in an incorrect URL being opened in the browser when requested using the webbrowser module.

* Correct the arguments passed to the Opera Browser when opening a new URL..
(cherry picked from commit 3cf1f154)
Co-authored-by: Bumsik Kim <k.bumsik@gmail.com>

Most of the change involves fixing up the test suite, which previously made
the assumption that there wouldn't be a new line if the input didn't end in
one.

Contributed by Ammar Askar.

(cherry picked from commit c4ef4896)