title: Angular 2 - Endless loop in async pipe
body: <p>I`m getting an endless loop when I try to bind a async function like this: </p>
  
  <pre><code>&lt;tr *ngFor="let i of items"&gt;
       &lt;td&gt;{{myAsyncFunc(i) | async}}&lt;/td&gt;
  &lt;/tr&gt;
  </code></pre>
  
  <p>this is the function: </p>
  
  <pre><code>private myAsyncFunc(i: string): Promise&lt;string&gt; {
          return Promise.resolve("some");
  }
  </code></pre>
  
  <p>I'm doing something wrong? Or this is a bug? </p>