Automerge-Triggered-By: @ned-deily

The purpose of the `unicodedata.is_normalized` function is to answer
the question `str == unicodedata.normalized(form, str)` more
efficiently than writing just that, by using the "quick check"
optimization described in the Unicode standard in UAX #15.

However, it turns out the code doesn't implement the full algorithm
from the standard, and as a result we often miss the optimization and
end up having to compute the whole normalized string after all.

Implement the standard's algorithm.  This greatly speeds up
`unicodedata.is_normalized` in many cases where our partial variant
of quick-check had been returning MAYBE and the standard algorithm
returns NO.

At a quick test on my desktop, the existing code takes about 4.4 ms/MB
(so 4.4 ns per byte) when the partial quick-check returns MAYBE and it
has to do the slow normalize-and-compare:

  $ build.base/python -m timeit -s 'import unicodedata; s = "\uf900"*500000' \
      -- 'unicodedata.is_normalized("NFD", s)'
  50 loops, best of 5: 4.39 msec per loop

With this patch, it gets the answer instantly (58 ns) on the same 1 MB
string:

  $ build.dev/python -m timeit -s 'import unicodedata; s = "\uf900"*500000' \
      -- 'unicodedata.is_normalized("NFD", s)'
  5000000 loops, best of 5: 58.2 nsec per loop

This restores a small optimization that the original version of this
code had for the `unicodedata.normalize` use case.

With this, that case is actually faster than in master!

$ build.base/python -m timeit -s 'import unicodedata; s = "\u0338"*500000' \
    -- 'unicodedata.normalize("NFD", s)'
500 loops, best of 5: 561 usec per loop

$ build.dev/python -m timeit -s 'import unicodedata; s = "\u0338"*500000' \
    -- 'unicodedata.normalize("NFD", s)'
500 loops, best of 5: 512 usec per loop

The HTML5 output from Sphinx 2.x adds  '<p>' tags within list elements.  Using a new prevtag attribute, ignore these instead of emitting unwanted '\n\n'.

Also stop looking for 'first' classes on tags (no longer present) and fix the bug of double-spacing instead of single spacing after <pre> blocks.

Extending the hover delay in test_tooltip should avoid spurious test_idle failures.
One longer delay instead of two shorter delays results in a net speedup.

-`"""` over `'''`
-no blank line either before or after the docstring.
-place the closing quotes on a line by themselves

* Fix suspicious.py to actually print the unused rules

* Fix the other `self.warn` calls

Sync importlib.metadata with importlib_metadata 0.20.

* Use the 'p' format unit instead of manually called PyObject_IsTrue().
* Pass boolean value instead 0/1 integers to functions that needs boolean.
* Convert some arguments to boolean only once.

Only AttributeError should be silenced.

Remove methods Element.getchildren(), Element.getiterator() and
ElementTree.getiterator() and the xml.etree.cElementTree module.

Fixes a case in which email._header_value_parser.get_unstructured hangs the system for some invalid headers. This covers the cases in which the header contains either:
- a case without trailing whitespace
- an invalid encoded word

https://bugs.python.org/issue37764

This fix should also be backported to 3.7 and 3.8


https://bugs.python.org/issue37764

MSVC 2015 supports %zd / %zu.  "z" is portable enough nowadays.

Fix a ctypes regression of Python 3.8. When a ctypes.Structure is
passed by copy to a function, ctypes internals created a temporary
object which had the side effect of calling the structure finalizer
(__del__) twice. The Python semantics requires a finalizer to be
called exactly once. Fix ctypes internals to no longer call the
finalizer twice.

Create a new internal StructParam_Type which is only used by
_ctypes_callproc() to call PyMem_Free(ptr) on Py_DECREF(argument).
StructUnionType_paramfunc() creates such object.

when built on non-Windows system without fd system call support,
like older versions of macOS.

Fix faulthandler.cancel_dump_traceback_later() call
if cancel_dump_traceback_later() was not called previously.

Adds a link to `dateutil.parser.isoparse` in the documentation.

It would be nice to set up intersphinx for things like this, but I think we can leave that for a separate PR.

CC: @pitrou 

[bpo-37979](https://bugs.python.org/issue37979)


https://bugs.python.org/issue37979



Automerge-Triggered-By: @pitrou

With `symtable_visit_expr` now correctly adjusting the recursion depth for named
expressions, `symtable_handle_namedexpr` should be leaving it alone.

Also adds a new check to `PySymtable_BuildObject` that raises `SystemError`
if a successful first symbol analysis pass fails to keep the stack depth
accounting clean.

Added tests for PyDateTime_xxx_GET_xxx() macros of the C API of
the datetime module.