weakref callbacks.

This is 2e446e87ac5b except that collections/__init__.py has been
modified to import proxy from _weakref instead of weakref.  This
eliminates an import cycle which seems to cause a problem on Unix but
not Windows.

Note that this is a potentially disruptive change since it may
release some system resources which would otherwise remain
perpetually alive (e.g. database connections kept in thread-local
storage).

weakref callbacks.

(thanks Arfrever for reporting).

(thanks Arfrever for reporting).

legitimately false.

Windows.

other tests.

Issue #17408: Avoid using an obsolete instance of the copyreg module when the interpreter is shutdown and then started again.

Issue #17408: Avoid using an obsolete instance of the copyreg module when the interpreter is shutdown and then started again.

Issue #5845: Enable tab-completion in the interactive interpreter by default, thanks to a new sys.__interactivehook__.

(original patch by Éric Araujo)

attributes to None.

The long-term goal is for people to be able to rely on these
attributes existing and checking for None to see if they have been
set. Since import itself sets these attributes when a loader does not
the only instances when the attributes are None are from someone
overloading __import__() and not using a loader or someone creating a
module from scratch.

This patch also unifies module initialization. Before you could have
different attributes with default values depending on how the module
object was created. Now the only way to not get the same default set
of attributes is to circumvent initialization by calling
ModuleType.__new__() directly.

trying to load an extension module.

While at it, also add a proper unittest.skipIf() guard to another test
involving imp.load_dynamic().

Issue #13721: SSLSocket.getpeercert() and SSLSocket.do_handshake() now raise an OSError with ENOTCONN, instead of an AttributeError, when the SSLSocket is not connected.