Inconsistency in the format docstring (2.7).

[jmfauth]

Small inconsistency in the format.__doc__

>>> sys.version
2.7 (r27:82525, Jul  4 2010, 09:01:59) [MSC v.1500 32 bit (Intel)]
>>> ''.format.__doc__
S.format(*args, **kwargs) -> unicode


>>> type('{}'.format(999))
<type 'str'>
>>> type('{}'.format('abcé'))
<type 'str'>