Angular ngClass bug

http://angularjs.org/

HTML

<div ng-controller="MyCtrl">
<div ng-class="{foo:!a}">I should be black</div>
</div>

<!-- black -->
<!--<script src="//code.angularjs.org/1.0.2/angular.min.js" type="text/javascript"></script>-->
<!-- red -->
<script src="//code.angularjs.org/1.0.3/angular.min.js" type="text/javascript"></script>

CSS

.foo {
    color: red;
}

JavaScript

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

function MyCtrl($scope) {
    $scope.a = false;
    $scope.x = [];
    $scope.$watch("x", function() {
        $scope.a = true;
    }, true);
    $scope.x.push(1);
}

function OtherCtrl($scope) {}