Fix require-final-newline interaction with read-only buffers.

* lisp/files.el (after-find-file): Do not try to add a final newline
if the buffer is read-only.

Fixes: debbugs:11156

lisp/ChangeLog

+2012-04-18  Christopher Schmidt  <christopher@ch.ristopher.com>
+
+	* files.el (after-find-file): Do not try to add a final newline if
+	the buffer is read-only (Bug#11156).
+
 2012-04-17  Richard Stallman  <rms@gnu.org>
 
 	* mail/rmail.el (rmail-start-mail):
@@ -9,7 +14,7 @@
 	(rmail-forward): Pass the Rmail buffer, not nil, for replybuffer.
 
 	* mail/sendmail.el (mail-bury): Choose the first rmail-mode
-	buffer, not the last.  Reject temp buffers.  Use the rmail-mode	
+	buffer, not the last.  Reject temp buffers.  Use the rmail-mode
 	buffer, not newbuf.
 
 2012-04-17  Juanma Barranquero  <lekktu@gmail.com>

lisp/files.el

@@ -2152,6 +2152,7 @@ unless NOMODES is non-nil."
 	 (/= (char-after (1- (point-max))) ?\n)
 	 (not (and (eq selective-display t)
 		   (= (char-after (1- (point-max))) ?\r)))
+	 (not buffer-read-only)
 	 (save-excursion
 	   (goto-char (point-max))
 	   (insert "\n")))