$emit bug

<!DOCTYPE html>
<html ng-app="plnkrApp">

<head>
  <script data-require="angular.js@1.3.16" data-semver="1.3.16" src="https://code.angularjs.org/1.3.16/angular.js"></script>
  <link rel="stylesheet" href="style.css" />
  <meta charset="UTF-8" />
  <script src="script.js"></script>
</head>

<body>
  <pre>
Tree of scopes: 
1 ($rootScope)
 └ 2 ($scope of ParentCtrl)
    └ 3 ($scope of ChildCtrl)
       └ 4 ($scope of GrandChildCtrl)
    </pre> {{ $id }}
  <div ng-controller="ParentCtrl" style="border: 1px solid red">
    {{$id}}
    <br>

    <div ng-controller="ChildCtrl" style="border: 1px solid green">
      {{$id}}
      <br>

      <div ng-controller="GrandChildCtrl" style="border: 1px solid blue">
        {{$id}}
        <br>
        <button ng-click="emitEvent()">Emit !</button>
      </div>

      <pre ng-show="sync$id">
      event.currentScope.$id is : {{sync$id}}
      Few millis later, event.currentScope.$id is : {{async$id||'undefined'}}</pre>
    </div>

    <pre ng-show="sync$id">
      event.currentScope.$id is : {{sync$id}}
      Few millis later, event.currentScope.$id is : {{async$id||'undefined'}}</pre>
  </div>

</body>

</html>


angular.module('plnkrApp', [])
  .controller('ParentCtrl', function($scope, $timeout) {
    $scope.$on('customEvent', function(event) {
      console.log(event.currentScope); // 003 the good one
      $scope.sync$id = event.currentScope.$id;
      $timeout(function() {
        console.log(event.currentScope) // 002 the $rootScope
        $scope.async$id = event.currentScope.$id;
      });
    })
  })
  .controller('ChildCtrl', function($scope, $timeout) {
    $scope.$on('customEvent', function(event) {
      console.log(event.currentScope); // 004 the good one
      $scope.sync$id = event.currentScope.$id;
      $timeout(function() {
        console.log(event.currentScope) // 002 the $rootScope
        $scope.async$id = event.currentScope.$id;
      });
    })
  })
  .controller('GrandChildCtrl', function($scope) {
    $scope.emitEvent = function() {
      $scope.$emit('customEvent');
    };
  });

/* Styles go here */

div, li {
  padding: 5px;
}