commit b0e79741aa66bd76ee1d69d524d5a661bf7a9f9b (HEAD, refs/remotes/origin/master)
Author: Alan Mackenzie <acm@muc.de>
Date:   Thu Nov 24 20:34:42 2016 +0000

    Handle correctly an (undocumented) bare mode in hack-local-variables.
    
    lisp/files.el (hack-local-variables-prop-line): When a file's first line
    contains only a mode specification without the string "mode:", return the mode
    symbol only when `handle-mode' is t.

diff --git a/lisp/files.el b/lisp/files.el
index 7c56f54..c56ff1d 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -3250,7 +3250,7 @@ return as the symbol specifying the mode."
 	       nil)
 	      ((looking-at "[ \t]*\\([^ \t\n\r:;]+\\)\\([ \t]*-\\*-\\)")
 	       ;; Simple form: "-*- MODENAME -*-".
-	       (if (memq handle-mode '(nil t))
+	       (if (eq handle-mode t)
 		   (intern (concat (match-string 1) "-mode"))))
 	      (t
 	       ;; Hairy form: '-*-' [ <variable> ':' <value> ';' ]* '-*-'