jQuery UI datepicker not selecting the correct month in 1.12.1

Question

When loading jQuery 3.1.1 and jQuery UI 1.12.1 (both production versions) the datepicker forward and back arrows do not take you to the proper months when numberOfMonths is greater than 1 and showCurrentAtPos is greater than 0.

The HTML is:

<input type=text id=selector />

The javaScript code to create the datepicker is very basic:

jQuery('#selector').datepicker({
 stepMonths: 1,
 numberOfMonths: 2,
 showCurrentAtPos: 1,
 dateFormat: 'yy-mm-dd',
 showOtherMonths: true,
 selectOtherMonths: true,
 showButtonPanel: true
});

Here is an example of the broken behavior:

jsFiddle

To get it to work properly, I had to load the GIT version 1.12.0-pre

Here is an example of it working as it should:

jsFiddle

Any suggestions? I'd prefer to use the production version of jQuery UI, but in this case, that isn't working.

jQuery UI Bug Ticket

Someone beat me to it, my bug ticket was a duplicate.

The (currently) open ticket is: jQuery UI Bug Ticket