* bpo-31479: Always reset the signal alarm in tests

Use "try: ... finally: signal.signal(0)" pattern to make sure that
tests don't "leak" a pending fatal signal alarm.

* Move two more alarm() calls into the try block

Fix also typo: replace signal.signal(0) with signal.alarm(0)

* Move another signal.alarm() into the try block

bpo-31293: Fix crashes in truediv and mul of a timedelta by a float with a bad as_integer_ratio() method. (#3227)

bpo-31315: Fix an assertion failure in imp.create_dynamic(), when spec.name is not a string. (#3257)

* Trivial cleanups following bpo-31370

* Also cleanup the "importlib._bootstrap_external" module

* bpo-31499, xml.etree: Fix xmlparser_gc_clear() crash

xml.etree: xmlparser_gc_clear() now sets self.parser to NULL to prevent a
crash in xmlparser_dealloc() if xmlparser_gc_clear() was called previously
by the garbage collector, because the parser was part of a reference cycle.
Co-Authored-By: Serhiy Storchaka <storchaka@gmail.com>

This reverses a never-released regression resulting from bpo-31287.

This function returns the last component of tp_name after a dot.
Returns tp_name itself if it doesn't contain a dot.

bpo-31482: Missing bytes support for random.seed() version 1 #3614

Shorten the comment to: "using integer format specifier"

bpo-31490: Fix an assertion failure in ctypes in case an _anonymous_ attr is defined only outside _fields_. (#3615)

Canceling timers prevents a warning message when test_idle completes.
(This is the minimum fix needed before upcoming releases.)

Provide additional examples of using format specifiers in f-strings
Added examples for using integer and date format specifiers.

When apply changes, call .reload on each class with non-key options.
Change ParenMatch so that updates affect current instances.

The concrete PyDict_* API is used to interact with PyInterpreterState.modules in a number of places. This isn't compatible with all dict subclasses, nor with other Mapping implementations. This patch switches the concrete API usage to the corresponding abstract API calls.

We also add a PyImport_GetModule() function (and some other helpers) to reduce a bunch of code duplication.

Signed-off-by: Christian Heimes <christian@python.org>

Replaces PROTOCOL_TLSv* and PROTOCOL_SSLv23 with PROTOCOL_TLS_CLIENT and
PROTOCOL_TLS_SERVER.
Signed-off-by: Christian Heimes <christian@python.org>

SSLSocket.wrap_bio() and SSLSocket.wrap_socket() hard-code SSLObject and
SSLSocket as return types. In the light of future deprecation of
ssl.wrap_socket() module function and direct instantiation of SSLSocket,
it is desirable to make the return type of SSLSocket.wrap_bio() and
SSLSocket.wrap_socket() customizable.
Signed-off-by: Christian Heimes <christian@python.org>

'Strip trailing whitespace' is not limited to spaces.  Wording caters to beginners who
do know know the meaning of 'whitespace'.  Multiline string literals are not skipped.

* News blurb.

Give 30 seconds to join_process(), instead of 5 or 10 seconds, to
wait until the process completes.

Call the .join() method of threading.Timer timers to prevent the
"threading_cleanup() failed to cleanup 1 threads" warning.

* Add Py_UNREACHABLE() as an alias to abort().
* Use Py_UNREACHABLE() instead of assert(0)
* Convert more unreachable code to use Py_UNREACHABLE()
* Document Py_UNREACHABLE() and a few other macros.

Enabled by default was a temporary expedient.  The fix is to add a user override to enable.

New -n flag allow overriding localhost with custom value,
for example to run from containers.

Fix Coverity CID 1417587: _PyMem_Initialize() contains code which is
never executed.

Replace the runtime check with a build assertion.