AngularJS ng-include

HTML

<div ng-controller="Ctrl">
    <div ng-include src="'template.html'"></div>
  </div>
  
<!-- template -->
<script type="text/ng-template" id="template.html">
    <input ng-model="testvalue" /><p/>
    Print testvalue: <b>{{testvalue}}</b>
    <p/>
    <a href="#" ng-click="show()">Show testvalue</a><p/>
    (this should alert the updated value, but instead it always shows the initial value. Why?)
</script>

JavaScript

function Ctrl($scope) {

   $scope.testvalue= "initial value";
    
   $scope.show = function(){
        alert($scope.testvalue);  
   }
}