bug#20396: 24.5; incorrect subject in replies

[Glenn Morris]

Nicolas Graner wrote:

> When you reply to a message whose Subject starts with "Re: ", this is
> normally stripped from the Subject before a new "Re: " is added in the
> reply. But if the Subject is RFC2047-encoded, stripping does not
> happen and you end up with "Re: Re: " in the reply.

Thanks for the report. Does this fix it?
(Apply patch, M-x emacs-lisp-byte-compile-and-load rmail.el)

--- a/lisp/mail/rmail.el
+++ b/lisp/mail/rmail.el
@@ -3830,7 +3830,8 @@ use \\[mail-yank-original] to yank the original message 
into it."
 ;;;      (setq cc resent-cc)))
     ;; Add `Re: ' to subject if not there already.
     (and (stringp subject)
-        (setq subject
+        (setq subject (rfc2047-decode-string subject)
+              subject
               (concat rmail-reply-prefix
                       (if (let ((case-fold-search t))
                             (string-match rmail-reply-regexp subject))