title: angular 2, select with dynamic option issues
body: <p>In Angular 2, I create a select with dynamic options, options (item array) will be changed </p>
  
  <pre><code>&lt;select [(ngModel)]="itemFilter" (change)="onChange($event)"&gt;
      &lt;option *ngFor="let item of items" [ngValue]="item.name"&gt;{{item.name}}&lt;/option&gt;
  &lt;/select&gt;
  </code></pre>
  
  <ol>
  <li>item array is blank, then the select is empty with blank</li>
  <li>item array is ["abc"], select contained "abc", then I select the "abc"</li>
  <li>item array becomes ["abc", "def"] and select contained "abc","def" options but the selected "abc" become blank, ngModel is still "abc" but just the select display blank and it looks like it select blank</li>
  </ol>
  
  <p>I assume that ngModel value is "abc" but the options (item array) is changed, then the ngModel binding is broken so the selected item become blank</p>
  
  <p>Did anyone come across the similar issue?</p>