Add PEP-411-compliant note about asyncio being provisional. Fixes issue #22346.
Issue #22346: also include asyncio PEP 411 notice in 3.4

--HG--
branch : 3.4
Null merge from 3.4 backport
Issue #22295: Adopt 'python -m pip' as the preferred invocation

--HG--
branch : 3.4
Merge issue #22295 fix from 3.4
Issue #22215: Now ValueError is raised instead of TypeError when str or bytes
argument contains not permitted null character or byte.
Issue #19524: Fixed resource leak in the HTTP connection when an invalid
response is received.  Patch by Martin Panter.

--HG--
branch : 3.4
Issue #19524: Fixed resource leak in the HTTP connection when an invalid
response is received.  Patch by Martin Panter.
Issue #22131: Modernized the code of the uuid module.

Optimized bytes and bytes_le properties of UUID and UUID constructor with
bytes_le argument.

Fixed a bug in handling an error occured during reading from a pipe in
_ipconfig_getnode().
Issue #22131: Fixed a bug in handling an error occured during reading from
a pipe in _ipconfig_getnode().

--HG--
branch : 3.4
Null merge
Issue #22226: Added private function _splitdict() in the Tkinter module.

First letter no longer is stripped from the "status" key in
the result of Treeview.heading().

--HG--
branch : 3.4
Issue #22226: Added private function _splitdict() in the Tkinter module.

First letter no longer is stripped from the "status" key in
the result of Treeview.heading().
remove various dead version checks (closes #22349)

Patch from Thomas Kluyver.

--HG--
branch : 3.4
merge 3.4 (#22349)