Decorate can create a multipart message with no part headers

[Mark Sapiro]

If the message to be decorated is a single part message with no Content-*
headers and the message body contains non-us-ascii characters (note that
this is not a valid message), Decorate.process() will convert the message
to multipart/mixed with a text/plain part for the original body and
additional text/plain part(s) for msg_header and/or msg_footer.

The problem is the part that corresponds to the original message body has
no part headers which confuses some mail readers.

This is fixed in bzr for 2.1.11.

[http://sourceforge.net/tracker/index.php?func=detail&aid=1991348&group_id=103&atid=100103]