Use without-restriction in with-temporary-notmuch-message-buffer

This ensures that the temporary copy of the current message-mode
buffer is whole and not limited by a current restriction.

An example of such restriction is the default one established by
message-mode when composing a reply, that hides the References,
In-Reply-To and similar headers.

emacs/notmuch-maildir-fcc.el

@@ -145,14 +145,15 @@ Otherwise set it according to `notmuch-fcc-dirs'."
 
 (defmacro with-temporary-notmuch-message-buffer (&rest body)
   "Set-up a temporary copy of the current message-mode buffer."
-  `(let ((case-fold-search t)
+  `(without-restriction
+     (let ((case-fold-search t)
 	   (buf (current-buffer))
 	   (mml-externalize-attachments message-fcc-externalize-attachments))
        (with-current-buffer (get-buffer-create " *message temp*")
 	 (message-clone-locals buf) ;; for message-encoded-mail-cache
 	 (erase-buffer)
 	 (insert-buffer-substring buf)
-       ,@body)))
+	 ,@body))))
 
 (defun notmuch-maildir-setup-message-for-saving ()
   "Setup message for saving.

test/T630-emacs-draft.sh

@@ -71,4 +71,36 @@ Fcc: MAIL_DIR/sent
 <#secure method=pgpmime mode=sign>
 EOF
 test_expect_equal_file EXPECTED OUTPUT.clean
+
+add_email_corpus attachment
+test_begin_subtest "Saving a draft keeps hidden headers"
+test_emacs '(notmuch-mua-new-reply "id:874llc2bkp.fsf@curie.anarc.at")
+            (message-goto-subject)
+            (delete-line)
+            (insert "Subject: draft-test-reply\n")
+	    (test-output "DRAFT")
+	    (notmuch-draft-postpone)
+	    (notmuch-show "subject:draft-test-reply")
+	    (notmuch-show-resume-message)
+	    (test-output)'
+notmuch_dir_sanitize OUTPUT > OUTPUT.clean
+
+cat <<EOF > EXPECTED
+References: <87d10042pu.fsf@curie.anarc.at> <87woy8vx7i.fsf@tesseract.cs.unb.ca> <87a7v42bv9.fsf@curie.anarc.at> <874llc2bkp.fsf@curie.anarc.at>
+From: Notmuch Test Suite <test_suite@notmuchmail.org>
+To: Antoine Beaupré <anarcat@orangeseeds.org>
+Subject: draft-test-reply
+In-Reply-To: <874llc2bkp.fsf@curie.anarc.at>
+Fcc: MAIL_DIR/sent
+--text follows this line--
+Antoine Beaupré <anarcat@orangeseeds.org> writes:
+
+> And obviously I forget the frigging attachment.
+>
+>
+> PS: don't we have a "you forgot to actually attach the damn file" plugin
+> when we detect the word "attachment" and there's no attach? :p
+EOF
+test_expect_equal_file EXPECTED OUTPUT.clean
+
 test_done