* lisp/bindings.el (buffer-file-coding-system):

Add explicit permanent-local mark.

; * src/buffer.c (init_buffer_once): Comment.

lisp/bindings.el

@@ -689,6 +689,7 @@ okay.  See `mode-line-format'.")
 ;; `kill-all-local-variables', because they have no default value.
 ;; For consistency, we give them the `permanent-local' property, even
 ;; though `kill-all-local-variables' does not actually consult it.
+;; See init_buffer_once in buffer.c for the origins of this list.
 
 (mapc (lambda (sym) (put sym 'permanent-local t))
       '(buffer-file-name default-directory buffer-backed-up
@@ -697,7 +698,8 @@ okay.  See `mode-line-format'.")
 	point-before-scroll buffer-file-truename
 	buffer-file-format buffer-auto-save-file-format
 	buffer-display-count buffer-display-time
-	enable-multibyte-characters))
+	enable-multibyte-characters
+	buffer-file-coding-system))
 
 ;; We have base64, md5 and sha1 functions built in now.
 (provide 'base64)

src/buffer.c

@@ -5079,6 +5079,8 @@ init_buffer_once (void)
 {
   int idx;
 
+  /* Items flagged permanent get an explicit permanent-local property
+     added in bindings.el, for clarity.  */
   memset (buffer_permanent_local_flags, 0, sizeof buffer_permanent_local_flags);
 
   /* 0 means not a lisp var, -1 means always local, else mask.  */