[PATCH] Fix mml-quoting in responses where pgp-signing is enabled

[Tim Bielawa]

The addition of mml-quote-region (notmuch-mua.el) in 2c6710e3 breaks
automatic signing in replies. When replies are mml-quoted and signing
is enabled by default the "<#part sign=pgpmime>" string will appear on
line 1. This will be consumed during the application of the
mml-quote-region function and transform into the inert string
"<#!part sign=pgpmime>". The result is that responses will no longer
be signed by default.

This fix moves the point forward one line before applying the quoting
function.

Consideration: Clients not signing mail by default. The first line of
their responses would be skipped when the quoting function is
applied. This string takes this general form:

    On Sat, 03 Mar 2012 12:55:14 -0800, notmuch-request at notmuchmail.org wrote:

Because the string is generated by notmuch I don't believe this fix
introduces the possibility for malicious mml commands being omitted
from the quoting.
---
 emacs/notmuch-mua.el |   15 +++++++++++++--
 1 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/emacs/notmuch-mua.el b/emacs/notmuch-mua.el
index 4be7c13..d8ab2c0 100644
--- a/emacs/notmuch-mua.el
+++ b/emacs/notmuch-mua.el
@@ -114,14 +114,25 @@ list."
       (goto-char (point-max)))
     (insert body)
     (push-mark))
-  (set-buffer-modified-p nil)
 
   (message-goto-body)
   ;; Original message may contain (malicious) MML tags.  We must
   ;; properly quote them in the reply.  Note that using `point-max'
   ;; instead of `mark' here is wrong.  The buffer may include user's
   ;; signature which should not be MML-quoted.
-  (mml-quote-region (point) (mark)))
+  ;;
+  ;; Note also that we skip the first line of the response as it is
+  ;; either: the "<#part sign=pgpmime>" string when clients use
+  ;; automatic signing, or it is the generated string from notmuch
+  ;; indicating the date and author of the message which is being
+  ;; responded to, "on date x, y z -0000, foo at bar.com wrote:"
+  (forward-line 1)
+  (mml-quote-region (point) (mark))
+
+  ;; Quoting the message may modify the contents of the buffer,
+  ;; however, we shouldn't consider mml-quoting a modification because
+  ;; it's preformed by the mua, not the user.
+  (set-buffer-modified-p nil))
 
 (defun notmuch-mua-forward-message ()
   (message-forward)
-- 
1.7.4.4