Correctly handle addresses whose username is an empty quoted string.

Add test cases for IDNA 2003 and 2008 host names. IDNA 2003
internationalized host names are working since bpo-31399 has landed. IDNA
2008 deviations are still broken and will be fixed in another patch.
Signed-off-by: Christian Heimes <christian@python.org>

Until now Python used a hard coded white list of default TLS cipher
suites. The old approach has multiple downsides. OpenSSL's default
selection was completely overruled. Python did neither benefit from new
cipher suites (ChaCha20, TLS 1.3 suites) nor blacklisted cipher suites.
For example we used to re-enable 3DES.

Python now defaults to OpenSSL DEFAULT cipher suite selection and black
lists all unwanted ciphers. Downstream vendors can override the default
cipher list with --with-ssl-default-suites.
Signed-off-by: Christian Heimes <christian@python.org>

This test is unstable and currently prevents to make any new change
since the test always fails on Travis CI.

Skip the test to get more time to fix it.

socketserver.ForkingMixIn.server_close() and
socketserver.ThreadingMixIn.server_close() now waits until all child
processes and non-daemonic threads complete.

The GIL is no longer created "on demand" to fix a race condition when
PyGILState_Ensure() is called in a non-Python thread.

To mitigate the situation when the buildbot is under load
and is unable to send/receive data fast enough:

* reduce the size of the payload
* set a generous timeout for socket ops

Add os.posix_spawn to wrap the low level POSIX API of the same name.

Contributed by Pablo Galindo.

Document the error return of PyLong_As* APIs.

A frequent Python C API usage error is neglecting to check the return
value and/or PyErr_Occurred().

This reverts commit 47c0b1f7.

Definition order of kwonly params is now guaranteed preserved.

I've run some tests on 3.7 asyncio and it appears that too many
things assume that run_in_executor returns a Future.

Ensure that ``truncate()`` preserves the file position (as reported by ``tell()``) after writes longer than the buffer size. 

It will be triggered when propagating an exception.

* bpo-32659: Solaris "stat" should support "st_fstype"

* Add 'versionadded'

Better account for single-line compound statements and
semi-colon separated statements when suggesting
Py3 replacements for Py2 print statements.

Initial patch by Nitish Chandra.

Updating the C API docs was missed when the per-opcode
tracing & profiling support was initially added.