title: update origin/master branch without checking that branch out
body: <p>I was under the assumption that:</p>
  
  <pre><code>git fetch origin
  </code></pre>
  
  <p>would update all the remote branches:</p>
  
  <pre><code>remotes/origin/master
  remotes/origin/dev
  </code></pre>
  
  <p>etc.</p>
  
  <p>but it turns out that doesn't seem to be the case and I can't figure out how these branches stay up to date, if it's not the case.</p>
  
  <p>how can I make sure my local remote branches are up to date? perhaps I will have better luck with:</p>
  
  <pre><code>git fetch origin master:master
  </code></pre>
  
  <p>?</p>