There is a race condition in create_connection() used with wait_for() to have a
timeout. sock_connect() registers the file descriptor of the socket to be
notified of write event (if connect() raises BlockingIOError). When
create_connection() is cancelled with a TimeoutError, sock_connect() coroutine
gets the exception, but it doesn't unregister the file descriptor for write
event. create_connection() gets the TimeoutError and closes the socket.

If you call again create_connection(), the new socket will likely gets the same
file descriptor, which is still registered in the selector. When sock_connect()
calls add_writer(), it tries to modify the entry instead of creating a new one.

This issue was originally reported in the Trollius project, but the bug comes
from Tulip in fact (Trollius is based on Tulip):
https://bitbucket.org/enovance/trollius/issue/15/after-timeouterror-on-wait_for

This change fixes the race condition. It also makes sock_connect() more
reliable (and portable) is sock.connect() raises an InterruptedError.

Without this reset, starttls would fail if a connect/starttls was done after a
quit, because smtplib assumed the existing value of emspt_features was
accurate, but it gets reset when starttls completes (and the new value does
not contain the starttls capability, since tls is already started at that
point).  (There may be additional places where this lack of reset was an
issue as well.)

Patch by Milan Oberkirch.

Issue #22185: Fix an occasional RuntimeError in threading.Condition.wait() caused by mutation of the waiters queue without holding the lock.

Patch by Doug Zongker.

Patch by Claudiu Popa.

Don't raise a TimeoutError if we reached the timeout and the future completed
in the same iteration of the event loop. A side effect of the bug is that
Queue.get() looses items.

than a potentially risky preexec_fn=os.setsid call.

Since a new demo can now be loaded while one is running,
adjust loadfile to do the same cleanup as stopIt.

with an external libmpdec.

to non-blocking mode. The non-blocking mode does not matter when using a
ProactorEventLoop, only for SelectorEventLoop.

* PipeServer.close() now cancels the "accept pipe" future which cancels the
  overlapped operation.
* Fix _SelectorTransport.__repr__() if the transport was closed
* Fix debug log in BaseEventLoop.create_connection(): get the socket object
  from the transport because SSL transport closes the old socket and creates a
  new SSL socket object. Remove also the _SelectorSslTransport._rawsock
  attribute: it contained the closed socket (not very useful) and it was not
  used.
* Issue #22063: socket operations (sock_recv, sock_sendall, sock_connect,
  sock_accept) of the proactor event loop don't raise an exception in debug
  mode if the socket are in blocking mode. Overlapped operations also work on
  blocking sockets.
* Fix unit tests in debug mode: mock a non-blocking socket for socket
  operations which now raise an exception if the socket is blocking.
* _fatal_error() method of _UnixReadPipeTransport and _UnixWritePipeTransport
  now log all exceptions in debug mode
* Don't log expected errors in unit tests
* Tulip issue 200: _WaitHandleFuture._unregister_wait() now catchs and logs
  exceptions.
* Tulip issue 200: Log errors in debug mode instead of simply ignoring them.

* dev: mention that the logging must be configured at DEBUG level
* streams: drain() has no more a strange return value, it's just
  a standard coroutine

posixpath.join().

window is created for every test class.

Fixed Tkinter images copying operations in NoDefaultRoot mode.

Tcl command names generated for "after" callbacks now contains a name of
original function.

python --generate-posix-vars in pybuilddir.txt build target by ensuring
that pybuilddir.txt is always regenerated when configure is run and
that the newly built skeleton python does not inadvertently import
modules from previously installed instances.

Thanks to Arfrever Frehtes Taifersar Arahesis.

it don't raise an exception if doraise is False.

Patch by Bohuslav "Slavek" Kabrda.

Thanks to Jon Poler for the patch.

Do not aggresively close wfile in the do_GET method in the BasicAuthHandler.

Fix Issue #8797: Raise HTTPError on failed Basic Authentication immediately. Initial patch by Sam Bull.

'As' became a full keyword when with statements were added in 2.5/2.6.

Patch from Thomas Kluyver.