(cherry picked from commit f76231f8)

(cherry picked from commit 92c2ca76)

(cherry picked from commit e0582a37)

(cherry picked from commit e197a853)

It can be removed after https://github.com/python/peps/commit/c28890fb421c906241da6da718f9eacc5a3109ee
(cherry picked from commit 7c9da3e5)

(cherry picked from commit e184cfd7)

(cherry picked from commit 5e0df74b)

(cherry picked from commit 191e9933)

* Fix compilation of the socket module on NetBSD 8.
* Fix the assertion failure or reading arbitrary data when parse
  a AF_BLUETOOTH address on NetBSD and DragonFly BSD.
* Fix other potential errors and make the code more reliable.
(cherry picked from commit d3187158)

(cherry picked from commit 01ae58d4)

(cherry picked from commit 0de92859)

bpo-31620: have asyncio/queues not leak memory when you've exceptions during waiting (GH-3813) (#4326)

(cherry picked from commit c62f0cb3)

(cherry picked from commit 5a66c8a6)

* bpo-31970: Reduce performance overhead of asyncio debug mode..
(cherry picked from commit 921e9432)

(cherry picked from commit 22b11285)

* fix doc for multiprocessing.connection.Client

The authenticate argument does not exist on either Client or Listener:
- https://github.com/python/cpython/blob/master/Lib/multiprocessing/connection.pyGH-L483 (master)
- https://github.com/python/cpython/blob/3.6/Lib/multiprocessing/connection.pyGH-L478 (3.6)
- https://github.com/python/cpython/blob/3.5/Lib/multiprocessing/connection.pyGH-L478 (3.5)
- https://github.com/python/cpython/blob/3.4/Lib/multiprocessing/connection.pyGH-L487 (3.4)
The documentation also claimed that these functions will call `current_process().auth_key`, for which I could find no evidence in the code. I rewrote the documentation to reflect the actual behavior.

Also made some small changes to vary sentence structure.
(cherry picked from commit 1e5d54cf)

By accident the size of the empty dict keys object matched the
size of values array.
(cherry picked from commit 39a156c5)

(cherry picked from commit cb04f751)

(cherry picked from commit 4135c893)

bpo-31764: Prevent a crash in sqlite3.Cursor.close() in case the Cursor object is uninitialized (GH-3958) (#4303)

(cherry picked from commit edb13ae4)

bpo-31770: Prevent a crash and refleaks when calling sqlite3.Cursor.__init__() more than once (GH-3968) (#4301)

(cherry picked from commit e56ab746)

Manual partial backport of patch that fixed nearly 50 other files.

(cherry picked from commit aed08562)

(cherry picked from commit 0d2a9088)

(cherry picked from commit aafece7a)

(cherry picked from commit 82cd3ced)

(cherry picked from commit b838cc3f)

* Using ifconfig on NetBSD and OpenBSD.
* Using arp on Linux, FreeBSD, NetBSD and OpenBSD.

Based on patch by Takayuki Shimizukawa.
(cherry picked from commit ee1a9a2b)

(cherry picked from commit a7723d8b)

All Blake2 params have to be encoded in little-endian byte order. For
the two multi-byte integer params, leaf_length and node_offset, that
means that assigning a native-endian integer to them appears to work on
little-endian platforms, but gives the wrong result on big-endian. The
current libb2 API doesn't make that very clear, and @sneves is working
on new API functions in the GH issue above. In the meantime, we can work
around the problem by explicitly assigning little-endian values to the
parameter block.

See https://github.com/BLAKE2/libb2/issues/12.
(cherry picked from commit dcfb0e3c)

Bug report and patch by Jeroen Demeyer.
(cherry picked from commit f6f90ff0)

[3.6] bpo-31310: multiprocessing's semaphore tracker should be launched again if crashed (GH-3247) (#4254)

* bpo-31310: multiprocessing's semaphore tracker should be launched again if crashed

* Avoid mucking with process state in test.
Add a warning if the semaphore process died, as semaphores may then be leaked.

* Add NEWS entry
(cherry picked from commit cbe1756e)

When a single .c file contains several functions and/or methods with
the same name, a safety _METHODDEF GH-define statement is generated
only for one of them.

This fixes the bug by using the full name of the function to avoid
duplicates rather than just the name..
(cherry picked from commit 4f57409a)

[3.6] bpo-31308: If multiprocessing's forkserver dies, launch it again when necessary (GH-3246) (#4252)

* bpo-31308: If multiprocessing's forkserver dies, launch it again when necessary.

* Fix test on Windows

* Add NEWS entry

* Adopt a different approach: ignore SIGINT and SIGTERM, as in semaphore tracker.

* Fix comment

* Make sure the test doesn't muck with process state

* Also test previously-started processes

* Update 2017-08-30-17-59-36.bpo-31308.KbexyC.rst

* Avoid masking SIGTERM in forkserver.  It's not necessary and causes a race condition in test_many_processes..
(cherry picked from commit fc6b348b)

netrc file format doesn't support quotes and escapes.

See https://linux.die.net/man/5/netrc
(cherry picked from commit b24cd055)

(cherry picked from commit ac03c03b)

(cherry picked from commit 0d2c645d)

(cherry picked from commit 4f469c09)

Skip a test for unget_wch()/get_wch() on OpenBSD since they are broken
in ncurses 5.7.
(cherry picked from commit 7e68790f)