Angular 1.4 BETA Text Binding bug

HTML

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.4.1/angular.min.js"></script>
<body ng-app="myApp" ng-init="testObject={switch:false}">click that:
    <div switch ng-model="testObject.switch">
        <hr>transcluded input:
        <input type="checkbox" ng-model="testObject.switch">
        <hr>
    </div>
</body>

CSS

.switch {
    display:block;
    cursor:pointer;
    background:yellow;
}

JavaScript

var booleanSwitchModule = angular.module('myApp', []);


booleanSwitchModule.directive('switch', [

function () {
    return {
        scope: {},
        require: "?^ngModel",
        link: function (scope, elem, attr, ngModel) {
            var timesChanged = 0;           
                      
            scope.$watch(function() {return ngModel.$modelValue; }, function (val) {

                if (val != undefined) {
                    alert("model changed " + ++timesChanged + " times");

                    scope.switchPosition = scope.model;
                }
            });


        },
        restrict: 'EA',
        replace: true,
        transclude: true,
        template: '<label class="switch">' +
            'directive scope model: {{ngModel}}' +
            '<span ng-transclude></span>' +
            '</label>',
    }
}]);