Remove outdated statements about threading and imports.

Doc/library/multiprocessing.rst

@@ -120,9 +120,7 @@ processes:
           print(q.get())    # prints "[42, None, 'hello']"
           p.join()
 
-   Queues are thread and process safe, but note that they must never
+   Queues are thread and process safe.
-   be instantiated as a side effect of importing a module: this can lead
-   to a deadlock!  (see :ref:`threaded-imports`)
 
 **Pipes**
 

Doc/library/threading.rst

@@ -996,27 +996,3 @@ is equivalent to::
 Currently, :class:`Lock`, :class:`RLock`, :class:`Condition`,
 :class:`Semaphore`, and :class:`BoundedSemaphore` objects may be used as
 :keyword:`with` statement context managers.
-
-
-.. _threaded-imports:
-
-Importing in threaded code
---------------------------
-
-While the import machinery is thread-safe, there are two key restrictions on
-threaded imports due to inherent limitations in the way that thread-safety is
-provided:
-
-* Firstly, other than in the main module, an import should not have the
-  side effect of spawning a new thread and then waiting for that thread in
-  any way. Failing to abide by this restriction can lead to a deadlock if
-  the spawned thread directly or indirectly attempts to import a module.
-* Secondly, all import attempts must be completed before the interpreter
-  starts shutting itself down. This can be most easily achieved by only
-  performing imports from non-daemon threads created through the threading
-  module. Daemon threads and threads created directly with the thread
-  module will require some other form of synchronization to ensure they do
-  not attempt imports after system shutdown has commenced. Failure to
-  abide by this restriction will lead to intermittent exceptions and
-  crashes during interpreter shutdown (as the late imports attempt to
-  access machinery which is no longer in a valid state).