title: KnockoutJS losing previous value when loading options after value
body: <p>I'm feeding my options off an <code>AJAX</code> request, while the value is in the selection initially. However <code>Knockout</code> seems to delete values that aren't in the options on binding.</p>
  
  <p>Example: <a href="http://jsfiddle.net/EVzrH/" rel="nofollow">http://jsfiddle.net/EVzrH/</a></p>
  
  <p><code>Knockout</code> seems to use <code>selectExtensions</code> (line 1699 of v3) to read and write the selected option. In this new values are matched to indexes, and returned by again getting the index and matching to data.</p>
  
  <p>How can I save my data from being lost?</p>