Yukihiro Nakadaira noticed a typo in encode_7or8bit that was trying
to special case iso-2022 codecs. It turns out that the code in
question is never used, because whereas it was designed to trigger
if the payload encoding was eight bit but its output encoding was
7 bit, in practice the payload is always converted to the 7bit
encoding before encode_7or8bit is called. Patch by Shawat Anand.
Fixed a typo in the email.encoders module so that messages output using
an ISO-2022 character set will use a content-transfer-encoding of
7bit consistently. Previously if the input data had any eight bit
characters the output data would get marked as 8bit even though it
was actually 7bit.