Also, give assignment to None a better error message

and then remove it. Written by Guilherme Polo (gpolo).

This fixes "from __future__ import unicode_literals" in an exec statment
See #4225

Issue #4237: io.FileIO() was raising invalid warnings caused by insufficient initialization of PyFileIOObject struct members.

does not return an iterator for the 4th and 5th items.
(sequence-like and mapping-like state)

A list is not an iterator...

Will backport to 2.6 and 2.5.

closefd=True is the only accepted value with a file name.

order to actually test what it was supposed to test, i.e. that the code
in the __del__ method did not crash.  Use instead the new helper
test_support.captured_output().