https://bugs.python.org/issue35401

Also adds the PC/layout script for generating layouts on Windows.

Propagate unexpected errors (like MemoryError and KeyboardInterrupt) to user.

Include <pyconfig.h> ealier in Modules/expat/xmltok.c to define
properly _POSIX_C_SOURCE. Python defines _POSIX_C_SOURCE as 200809L,
whereas <features.h> (included indirectly by <string.h>) defines
_POSIX_C_SOURCE as 199506L.

The length check for AF_ALG salg_name and salg_type had a off-by-one
error. The code assumed that both values are not necessarily NULL
terminated. However the Kernel code for alg_bind() ensures that the last
byte of both strings are NULL terminated.
Signed-off-by: Christian Heimes <christian@python.org>

Fix xml.dom.minidom cloneNode() on a document with an entity: pass
the correct arguments to the user data handler of an entity (fix an
old copy/paste mistake).

Bug spotted and fix proposed by Charalampos Stratakis, initial
reproducer written by Petr Viktorin.
Co-Authored-By: Charalampos Stratakis <cstratak@redhat.com>
Co-Authored-By: Petr Viktorin <encukou@gmail.com>

In _localemodule.c and selectmodule.c, remove dead code that would
cause double decrefs if run.

In addition, replace PyList_SetItem() with PyList_SET_ITEM() in cases
where a new list is populated and there is no possibility of an error.

In addition, check if the list changed size in the loop in array_array_fromlist().

* tests: Further validate `wraps` functionality in `unittest.mock.Mock`

Add more tests to validate how `wraps` interacts with other features of
mocks.

* Don't call the wrapped object if `side_effect` is set

When a object is wrapped using `Mock(wraps=...)`, if an user sets a
`side_effect` in one of their methods, return the value of `side_effect`
and don't call the original object.

* Refactor what to be called on `mock_call`

When a `Mock` is called, it should return looking up in the following
order: `side_effect`, `return_value`, `wraps`. If any of the first two
return `mock.DEFAULT`, lookup in the next option.

It makes no sense to check for `wraps` returning default, as it is
supposed to be the original implementation and there is nothing to
fallback to.

This reverts commit 468a15aa.

encoding='latin1' should be used for successful decoding.

Set MemoryError when appropriate, add missing failure checks,
and fix some potential leaks.

Replace os.popen() with subprocess.check_output() in the platform module:

* platform.uname() (its _syscmd_ver() helper function) now redirects
  stderr to DEVNULL.
* Remove platform.DEV_NULL.
* _syscmd_uname() and _syscmd_file() no longer catch AttributeError.
  The "except AttributeError:" was only needed in Python 2, when
  os.popen() was not always available. In Python 3,
  subprocess.check_output() is always available.

* bpo-34864: warn if "Prefer tabs when opening documents" set to "Always"

* add NEWS entry

* address code review comments

* address second code review comments

* Add entry for idlelib/NEWS.txt.

https://bugs.python.org/issue35434

The function is never imported and the implementation is actually buggy.
As `warnings.catch_warnings` is not imported here.

Join 3 pools in these tests:

* test.test_multiprocessing_spawn.WithProcessesTestPool.test_context
* test.test_multiprocessing_spawn.WithProcessesTestPool.test_traceback

This reverts commit 97bfe8d3.