AngularJS tabs example and IE8

I am using the tabs example on the AngularJS homepage. I essentially just pulled that code out verbatim so it looks like this:

app.directive('tabs', function() {
    return {
        restrict: 'E',
        transclude: true,
        scope: {},
        controller: function($scope, $element) {
            var panes = $scope.panes = [];

            $scope.select = function(pane) {
                angular.forEach(panes, function(pane) {
                    pane.selected = false;
                });
                pane.selected = true;
            }

            this.addPane = function(pane) {
                if (panes.length == 0) $scope.select(pane);
                panes.push(pane);
            }
        },
        template:
            '<div class="tabbable">' +
                '<ul class="nav nav-tabs">' +
                '<li ng-repeat="pane in panes" ng-class="{active:pane.selected}">'+
                '<a href="" ng-click="select(pane)">{{pane.title}}</a>' +
                '</li>' +
                '</ul>' +
                '<div class="tab-content" ng-transclude></div>' +
                '</div>',
        replace: true
    };
});

app.directive('pane', function() {
        return {
            require: '^tabs',
            restrict: 'E',
            transclude: true,
            scope: { title: '@' },
            link: function(scope, element, attrs, tabsCtrl) {
                tabsCtrl.addPane(scope);
            },
            template:
                '<div class="tab-pane" ng-class="{active: selected}" ng-transclude>' +
                    '</div>',
            replace: true
        };
    })

This is working great except in IE8 the actual tabs that you click on to change the current tab are missing and I get this console error:

  Error: No controller: tabs<div class=tab-pane title="Change Log" ng-class="{active: selected}" ng-transclude>

What could be going wrong in IE8?