title: Select box in Angular adding extra blank option
body: <p>I have a select/drop-down box in my Angularjs app:</p>
  
  <pre><code>&lt;select ng-model="places"&gt;
    &lt;option value="1"&gt;London&lt;/option&gt;
    &lt;option value="2"&gt;Paris&lt;/option&gt;
    &lt;option value="3"&gt;Madrid&lt;/option&gt;
    &lt;option value="4"&gt;Athens&lt;/option&gt;
  &lt;/select&gt;
  </code></pre>
  
  <p>but in the HTML page there is an extra blank <code>option</code> added above the London option. When I remove <code>ng-model</code> then it renders as I would expect (i.e. 4 options with London showing by default). Is this normal?</p>