py3: fix headencode() with display=False We previously called str() on a email.header.Header object. On Python 2, this returns a bytestring and the __str__ method is actually an alias to .encode() method. On Python 3, __str__ does not perform encoding (and returns a unicode string). To keep a consistent behavior across Python versions, we explicitly use .encode() and we wrap the result with encoding.strtolocal() to get a bytestring in all cases. As a side effect of forcing bytes conversion, we need to decode back in _addressencode(). This is to make test-notify.t pass on Python 3. Also note that headers are now encoded in some patchbomb tests; this is because the charset is not always "us-ascii" ("iso-8859-1" otherwise) on Python 3.