How do I use a custom month template with Angular UI Bootstrap Datepicker?

Question

In the case of Angular Bootstrap UI Datepicker, I am unable to duplicate the technique for overriding Angular Bootstrap UI templates shown at this plunkr, which is cited at SO here.

Here is my attempt:

angular.module('ui.bootstrap.demo').config(['$provide', Decorate]);

  function Decorate($provide) {
    $provide.decorator('datepickerDirective', function($delegate) {
      var directive = $delegate[0];
      directive.templateUrl = "calendarOverride.tpl.html";
      return $delegate;
    });
  }

And here is my attempt in action: plnkr.co/edit/xNPzXQHsHxomMmBPwOCc?p=preview

Notice that the calendar table does not show!

Thanks,

G