Thanx MacManX
This is a method of hiding the obvious wp-login.php from bots, using an alternate URL, rather than disabling the Dashboard. It’s referenced in the security section of an O’Reilly WordPress book.
I added it to my child theme’s functions.php, so don’t consider it a core hack. It’s a small piece of code that seems less complicated than loading another plugin. I am open to other methods, but it would be nice to know why this suddenly fails with the 3.9.2 wp-login.php and if there is a simple fix.