title: Drupal 8 strange caching issue
body: <p>I have weird caching issue on Drupal site.</p>
  
  <p>First D8 page caching is turned off.</p>
  
  <p>Then I have some content on page that changes for every page loading - to make it simple I'm printing current time from twig template:</p>
  
  <pre><code>{{ "now"|date("H:i:s") }}
  </code></pre>
  
  <p>It works like this:</p>
  
  <ul>
  <li>After clearing Drupal's cache and opening the page I can see current time, as expected</li>
  <li>When I reload the page I still see previous time (I'm logged in as master admin). No matter how many times I reload the page I see time of the first page loading after clearing the cache</li>
  <li>When I open the same page from another browser for the first time I see current time and after that for any reload I see time of the first page opening in that browser</li>
  <li>When I inspect page loading from browser it says that page is loaded from server  - not cached by browser</li>
  <li>Clearing cookies doesn't help. For the first time I clear the cookie I get logged out and I see current time once, but for every other cookie clearing I see the same time.</li>
  </ul>
  
  <p>Any idea what is happening here and how to disable that caching?</p>