(utf7-encode, utf7-decode): Use mm-with-multibyte-buffer, or

mm-with-unibyte-buffer, rather than default-enable-multibyte-characters.

lisp/gnus/utf7.el

 ;;; utf7.el --- UTF-7 encoding/decoding for Emacs   -*-coding: iso-8859-1;-*-
 
-;; Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004,
-;;   2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
+;; Copyright (C) 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007,
+;;   2008, 2009  Free Software Foundation, Inc.
 
 ;; Author: Jon K Hellan <hellan@acm.org>
 ;; Maintainer: bugs@gnus.org
@@ -210,23 +210,21 @@ Characters are in raw byte pairs in narrowed buffer."
   (if (and (coding-system-p 'utf-7) (coding-system-p 'utf-7-imap))
       ;; Emacs 23 with proper support for IMAP
       (encode-coding-string string (if for-imap 'utf-7-imap 'utf-7))
-    (let ((default-enable-multibyte-characters t))
-      (with-temp-buffer
-	(insert string)
-	(utf7-encode-internal for-imap)
-	(buffer-string)))))
+    (mm-with-multibyte-buffer
+     (insert string)
+     (utf7-encode-internal for-imap)
+     (buffer-string))))
 
 (defun utf7-decode (string &optional for-imap)
   "Decode UTF-7 STRING.  Use IMAP modification if FOR-IMAP is non-nil."
   (if (and (coding-system-p 'utf-7) (coding-system-p 'utf-7-imap))
       ;; Emacs 23 with proper support for IMAP
       (decode-coding-string string (if for-imap 'utf-7-imap 'utf-7))
-    (let ((default-enable-multibyte-characters nil))
-      (with-temp-buffer
-	(insert string)
-	(utf7-decode-internal for-imap)
-	(mm-enable-multibyte)
-	(buffer-string)))))
+    (mm-with-unibyte-buffer
+     (insert string)
+     (utf7-decode-internal for-imap)
+     (mm-enable-multibyte)
+     (buffer-string))))
 
 (provide 'utf7)