Fix two test cases in test_os.  ftruncate raises IOError unlike all the others which raise OSError.  And close() on some platforms doesn't complain when given an invalid file descriptor.

For datetime, gentoo didn't seem to mind the %e format for strftime.  So, we just excercise those instead making sure that we don't crash.
For test_os, two cases were incorrect.

Also, explicitly connect to the IPV4 address.  On windows platforms supporting AF_INET6, the SocketProxy would connect using socket.create_connection('localhost', port) which would cycle through all address families and try to connect.  It would try connecting using AF_INET6 first and this would cause a delay of up to a second.

e.g. a __slots__ attribute which has not been set.

("windows sprintf", different than swprintf)

Needed for the windows CE port.

to str, bytes and bytearray could be optimized away by the compiler, letting
the interpreter segfault instead of raising an error.

Needs to be backported to 2.6 and forward ported to 3.0 and 3.1.

Improve the appearance and flow of the References section -- it used
to have a box around it that wasn't distinct from the preceding code
boxes and it had a weird bolding pattern and hanging indents that
made the section disproportionately large.

with a mapping.  Makes Counter() idempotent, makes update()
API the same as Counter.__init__(), makes a more readable
repr, makes the API more dict-like, and allows Steven
Bethard's update() example to work.

Now the slot is filled with a function that always raises.

Will not backport: extensions compiled with 2.6.x would not run on 2.6.0.

Add tests for invalid format specifiers in strftime, and for handling of invalid file descriptors in the os module.