(backport from rev. 53477)

 (backport from rev. 52666)

string pointed to by its parameter.
 (backport from rev. 52078)

 (backport from rev. 51368)

Additionally, remove a faulty example showing PySequence_SetItem applied
to a newly created list object and add notes that this isn't a good idea.
 (backport from rev. 51364)

Replace UnicodeDecodeErrors raised during == and !=
compares of Unicode and other objects with a new
UnicodeWarning.

All other comparisons continue to raise exceptions.
Exceptions other than UnicodeDecodeErrors are also left
untouched.

I modified this patch some by fixing style, some error checking, and adding
XXX comments.  This patch requires review and some changes are to be expected.
I'm checking in now to get the greatest possible review and establish a
baseline for moving forward.  I don't want this to hold up release if possible.

PyThreadState_SetAsyncExc():  internal correctness changes wrt
refcount safety and deadlock avoidance.  Also added a basic test
case (relying on ctypes) and repaired the docs.

Is the explanation of the 'stacklevel' parameter clear?  Please feel free
to edit it.

I don't have LaTeX installed on this machine, so haven't verified that the
markup is correct.  Will check tonight, or maybe the automatic doc build will
tell me.

[Patch #1490989 from Skip Montanaro]  Mention debugging builds in the API documentation.  I've changed Skip's patch to point to Misc/SpecialBuilds and fiddled with the markup a bit.

tp_compare to tp_richcompare ;)

"base" parameter.

about "%u", "%lu" and "%zu" formats.

Since PyString_FromFormat and PyErr_Format have exactly the same rules
(both inherited from PyString_FromFormatV), it would be good if someone
with more LaTeX Fu changed one of them to just point to the other.
Their docs were way out of synch before this patch, and I just did a
mass copy+paste to repair that.

Not a backport candidate (this is a new feature).

by Collin Winter.

Bugfix candidate (but I'm not going to bother).

guillemets; no need for magic here

caller becomes the owner of that reference).

and PyObject_DEL.

Fixes part of #1445210.

adds the following API calls: PySet_Clear(), _PySet_Next(), and
_PySet_Update().  The latter two are considered non-public.  Tests and
documentation (for the public API) are included.