Fix importlib examples to insert any newly created modules via importlib.util.module_from_spec() immediately into sys.modules instead of after calling loader.exec_module().

Thanks to Benjamin Mintz for finding the bug.


https://bugs.python.org/issue37521

Move `threaded_import_hangers`, a dependency of `test_threaded_import`, to the directory `test_importlib/`. Also update the import references for `threaded_import_hangers` in `test_threaded_import`.





https://bugs.python.org/issue19696

The `arraymodule`'s `b_getitem` function returns a `PyLong` converted 
from `arrayobject`'s array, by dereferencing a pointer to `char`.

When the `char` type is `signed char`, the `if (x >= 128) x -= 256;` comparison/code is redundant because a `signed char` will have a value of `[-128, 127]` and so `x` will never be greater or equal than 128.

This check was indeed needed for situations where a given compiler would assume `char` being `unsigned char` which would make `x` in `[0, 256]` range.

However, the check can be removed if we cast the `ob_item` into a signed char pointer (`signed char*`) instead of `char*`.

This PR/commit introduces this change.

With the addition of shared memory into Python 3.8, we now have three tests failing on Solaris, namely `test_multiprocessing_fork`, `test_multiprocessing_forkserver` and `test_multiprocessing_spawn`. The reason seems to be incorrect name handling which results in two slashes being prepended.


https://bugs.python.org/issue37558

https://bugs.python.org/issue37554

uintptr_t is an integer type, and can't be compared to NULL directly.

Keeping an account of allocated blocks slows down _PyObject_Malloc()
and _PyObject_Free() by a measureable amount.  Have
_Py_GetAllocatedBlocks() iterate over the arenas to sum up the
allocated blocks for pymalloc.

After fcf1d003, IDLE startup failed with python compiled without docstrings.

test_ssl.test_pha_required_nocert() now uses
support.catch_threading_exception() to ignore the expected SSLError
in ConnectionHandler of ThreadedEchoServer (it is only raised
sometimes on Windows).

This reverts commit cf9c41c4.

Replace PyLong_FromLong() with PyLong_FromSize_t():
SSL_CTX_get_num_tickets() return type is size_t.


https://bugs.python.org/issue37120

Context manager catching threading.Thread exception using
threading.excepthook.

Close the TLS connection in test_pha_required_nocert() of test_ssl to
fix a ResourceWarning.

Nested BinOp instances (e.g. a+b+c) had a wrong col_offset for the
second BinOp (e.g. 2 instead of 0 in the example). Fix it by using the
correct st node to copy the line and col_offset from in ast.c.

Initial report by Michael Blankenship on docs@

test_concurrent_futures now explicitly stops the ForkServer instance
if it's running.

* bpo-37520: Correct behavior for zipfile.Path.parent

* 📜🤖 Added by blurb_it.

0 is a legal index.

This is done to compensate for the extra stack frames added by
IDLE itself, which cause problems when setting the recursion limit
to low values.

This wraps sys.setrecursionlimit() and sys.getrecursionlimit()
as invisibly as possible.

Also fix a name misspelling.

* accross -> across
* Extra space removed in comment