title: Glide preload doesn't save in cache
body: <p>I would like to preload images before they are showed to the user. I have a ViewPager where every page is an image. When the activity starts, it calls:</p>
  
  <pre><code>Glide.with(this).load(uri).preload();
  </code></pre>
  
  <p>After that all the images are preloaded (theoretically), in order to test if the preload works, I disable all network connections and I try to swype between the pages to load the images, but Glide doesn't load them.</p>
  
  <p>In my project, Glide is configured with default values.</p>
  
  <p>Furthermore, if I load the image swyping the viewpager (with internet connection), Glide saves the images in cache.</p>
  
  <p>I tried also using</p>
  
  <pre><code>Glide.with(this).load(uri).downloadOnly(x,y);
  </code></pre>
  
  <p>with the same results.</p>