org.el (org-fontify-meta-lines-and-blocks-1): Fix handling of `org-hidden-keywords'

* org.el (org-fontify-meta-lines-and-blocks-1): Fix handling
of `org-hidden-keywords'.

Thanks to Leu Zhe for reporting this.

lisp/org.el

@@ -5891,7 +5891,7 @@ by a #."
 	   ((member dc1 '("+title:" "+author:" "+email:" "+date:"))
 	    (add-text-properties
 	     beg (match-end 3)
-	     (if (member (intern (substring dc1 0 -1)) org-hidden-keywords)
+	     (if (member (intern (substring dc1 1 -1)) org-hidden-keywords)
 		 '(font-lock-fontified t invisible t)
 	       '(font-lock-fontified t face org-document-info-keyword)))
 	    (add-text-properties