changes to message-send-and-exit in Emacs 26

[Alex Bennée]

Hi,

I'm trying to track down what is happening in Emacs when I call
message-send-and-exit to send an email from mu4e. I mailed emacs-user:

  Subject: Changes to message-mode and encoding in Emacs26
  Date: Tue, 26 Sep 2017 16:41:03 +0100
  Message-ID: <address@hidden>

but I suspect the details of encoding need some input from developers.
So in brief why does the act of sending an email result in:

            character: é (displayed as é) (codepoint 233, #o351, #xe9)
    preferred charset: unicode-bmp (Unicode Basic Multilingual Plane 
(U+0000..U+FFFF))
code point in charset: 0xE9
               script: latin
               syntax: w        which means: word
             category: .:Base, L:Left-to-right (strong), c:Chinese, j:Japanese, 
l:Latin, v:Viet
             to input: type "C-x 8 RET e9" or "C-x 8 RET LATIN SMALL LETTER E 
WITH ACUTE"
          buffer code: #xC3 #xA9
            file code: #xC3 #xA9 (encoded by coding system utf-8-unix)
              display: terminal code #xC3 #xA9

ending up as:

            character:  (displayed as ) (codepoint 4194243, #o17777703, 
#x3fffc3)
    preferred charset: eight-bit (Raw bytes 128-255)
code point in charset: 0xC3
               syntax: w        which means: word
             category: L:Left-to-right (strong)
             to input: type "C-x 8 RET 3fffc3"
          buffer code: #xC3
            file code: not encodable by coding system utf-8-unix
              display: not encodable for terminal

Any pointers?

--
Alex Bennée