[docs] email.policy doc example passes 'policy' to as_string, but that doesn't work (issue 18600)

http://bugs.python.org/review/18600/diff/8864/Doc/library/email.message.rst File Doc/library/email.message.rst (right): http://bugs.python.org/review/18600/diff/8864/Doc/library/email.message.rst#... Doc/library/email.message.rst:43: .. method:: as_string(unixfrom=False, maxheaderlen=0, policy=None) You need a versionchanged tag for the new parameter. http://bugs.python.org/review/18600/diff/8864/Doc/library/email.message.rst#... Doc/library/email.message.rst:85: .. method:: as_bytes(unixfrom=False, policy=None) versionadded required. http://bugs.python.org/review/18600/diff/8864/Doc/library/email.message.rst#... Doc/library/email.message.rst:114: .. method:: __bytes__() versionadded required. http://bugs.python.org/review/18600/