title: Rails.cache.clear returns nil
body: <p>I have this setup 
  <code>config.cache_store = :redis_store, ENV['REDIS_CACHE_URL']</code></p>
  
  <pre><code>$ redis-cli
  127.0.0.1:6379&gt; set random_key 1
  OK
  </code></pre>
  
  <p>Now I go to the console and do <code>Rails.cache.clear</code> which returns nil</p>
  
  <p>And I am still able to access the key <code>random_key</code> in the redis-cli. It did not clear the cache.</p>
  
  <p>I could not read what <code>Rails.cache</code> returns here too <code>ruby/2.3.4/lib/ruby/gems/2.3.0/gems/railties-4.2.8/lib/rails.rb</code></p>
  
  <p><strong>Is Rails.cache.clear is supposed to return true?</strong></p>
  
  <p>Can someone please help me out if my understanding is wrong? </p>