* Misc gc code & comment cleanups.

validate_list:  there are two temp flags polluting pointers, but this checked only one.  Now it checks both, and verifies that the list head's pointers are not polluted.

move_unreachable: repaired incoherent comments.  Added new comments.  Cleared the pollution of the unreachable list head's 'next' pointer (it was expedient while the function was running, but there's no excuse for letting this damage survive the function's end).

* Update Modules/gcmodule.c
Co-Authored-By: Pablo Galindo <Pablogsal@gmail.com>

Metaclass was removed in Python 3.7 (there is already a `versionchanged` item about this).


https://bugs.python.org/issue28556

* Use Unicode character for accent
* Various grammar fixes
* Sort library modules alphabetically; remove duplicated idlelib/IDLE section

Currently if any finalizer invoked during garbage collection resurrects any object, the gc gives up and aborts the collection. Although finalizers are assured to only run once per object, this behaviour of the gc can lead to an ever-increasing memory situation if new resurrecting objects are allocated in every new gc collection.

To avoid this, recompute what objects among the unreachable set need to be resurrected and what objects can be safely collected. In this way, resurrecting objects will not block the collection of other objects in the unreachable set.

They conflicted with keyword "in".

Also rename positional-only parameters of private os._fcopyfile()
for consistency.

* bpo-38456: Use /bin/true in test_subprocess.

Instead of sys.executable, "-c", "pass" or "import sys; sys.exit(0)"
use /bin/true when it is available.  On a reasonable machine this
shaves up to two seconds wall time off the otherwise ~40sec execution
on a --with-pydebug build.  It should be more notable on many
buildbots or overloaded slower I/O systems (CI, etc).

On POSIX systems, allow the umask to be set in the child process before we exec.

This is a fairly noticeable change that requires adjustments in
existing asyncio code. It should therefore be announced.

Since `smtpd.MailmanProxy` is already broken, it is not formally deprecated in 3.9. It will be removed in 3.10.


https://bugs.python.org/issue35800

bpo-38449: Revert "bpo-22347: Update mimetypes.guess_type to allow oper parsing of URLs (GH-15522)" (GH-16724)



This reverts commit 87bd2071.



https://bugs.python.org/issue38449

 pathfix.py: Assume all files that end on '.py' are Python scripts when working recursively. 

Rewrite getsockaddrarg() helper function of socketmodule.c (_socket
module) to prevent a false alarm when compiling codde using GCC with
_FORTIFY_SOURCE=2. Pass a pointer of the sock_addr_t union, rather
than passing a pointer to a sockaddr structure.

Add "struct sockaddr_tipc tipc;" to the sock_addr_t union.

bpo-38353, bpo-38429: Fix typos introduced by commit
c02b41b1 in
calculate_argv0_path_framework() of getpath.c.

PR #4906 changed the typing.Generic class hierarchy, leaving an
outdated comment in the library reference. User-defined Generic ABCs now
must get a abc.ABCMeta metaclass from something other than typing.Generic
inheritance.

Add missing stat.S_IFDOOR, stat.S_IFPORT, stat.S_IFWHT,
stat.S_ISDOOR, stat.S_ISPORT, and stat.S_ISWHT values to
the Python implementation of the stat module.

bpo-38392, bpo-38426: Fix a compiler warning in gcmodule.c.

Fix also a typo in PYMEM_DEADBYTE macro comment.

* bpo-38379:  when a finalizer resurrects an object,
nothing is actually collected in this run of gc.
Change the stats to relect that truth.

Signed-off-by: Antonio Gutierrez <chibby0ne@gmail.com>

bpo-37531, bpo-38207: On timeout, regrtest no longer attempts to call
`popen.communicate() again: it can hang until all child processes
using stdout and stderr pipes completes. Kill the worker process and
ignores its output.

Reenable test_regrtest.test_multiprocessing_timeout().

bpo-37531: Change also the faulthandler timeout of the main process
from 1 minute to 5 minutes, for Python slowest buildbots.

The implementation of weakref.proxy's methods call back into the Python
API using a borrowed references of the weakly referenced object
(acquired via PyWeakref_GET_OBJECT). This API call may delete the last
reference to the object (either directly or via GC), leaving a dangling
pointer, which can be subsequently dereferenced.

To fix this, claim a temporary ownership of the referenced object when
calling the appropriate method. Some functions because at the moment they
do not need to access the borrowed referent, but to protect against
future changes to these functions, ownership need to be fixed in
all potentially affected methods.