title: knockout js subscribing to select list selected option is showing undefined repeatedly
body: <p>I have I drop down list prepopulated with a list of strings. My select list binding is like so:</p>
  
  <pre><code>&lt;select id="industryDropDown"
      data-bind="options: $root.orgIndustrySuggestions, value: $root.selectedIndustryTag, optionsCaption: ''"&gt;&lt;/select&gt;
  </code></pre>
  
  <p>In my viewmodel I have this: </p>
  
  <pre><code>self.selectedIndustryTag.subscribe(function (newValue) {
      if (newValue !== '') {
          if (newValue !== 'undefined')
              {
          alert(self.selectedIndustryTag());
          self.selectedIndustryTag('');
          }
      }
  }, self);
  </code></pre>
  
  <p>I am trying to get the selected value from the drop down list, do something where the alert() is now, and then reset the selected value to the default empty string option.</p>
  
  <p>Currently when I run this, page load is fine. But when I select something it will show me the selected value the first time, but them throw up a kajillion (i counted) alerts saying 'undefined' after that. </p>