title: How to force service worker to update?
body: <p>I'm using sw-precache to generate my service work with Polymer CLI build process, so it's intended to update the hash of updated files to signal a need to update the cache. But my updated content is not being replaced in cache, so it's getting an old version if I refresh with ctrl+r but the new version if I refresh with ctrl+shift+r. A reason for that can be that my service worker is not being updated.</p>
  
  <p><a href="https://developers.google.com/web/fundamentals/getting-started/primers/service-workers#update-a-service-worker" rel="noreferrer">This doc</a> states that </p>
  
  <blockquote>
    <p>If there is even a byte's difference in the service worker file
    compared to what it currently has, it considers it new.</p>
  </blockquote>
  
  <p>, but what if my new service worker didn't change a byte? (as it happens if just one hash has changed). How to configure the sw-precache to update the service work at every new request?</p>