title: React router wont trigger componentWillUnmount when the route is a sub-route
body: <p>I am not seeing react-router unmount component when the route is a sub-route</p>
  
  <p>So even if I switch between path/1 and path/2, componentWillUnmount never gets called for the instance of ComponentForRoute. Any suggestions? Is this how react-router is suppose to work? If so, any suggestions on handling route changes?</p>
  
  <p>Tried using componentWillReceiveProps, but i guess its deprecated now?</p>
  
  <pre><code>&lt;Router history={history}&gt;
      &lt;Route path="path/:paramId" component={ComponentForRoute} /&gt;
  &lt;/Router&gt;
  </code></pre>