title: git fetch remote branch and remote ref
body: <p>how do I fetch a remote branch and update git's local ref for that branch without effecting the current branch?  For example if I do this</p>
  
  <pre><code>$ git pull origin master
  </code></pre>
  
  <p>origin/master is merged into my current branch. This also doesn't work</p>
  
  <pre><code>$ git fetch origin master
  </code></pre>
  
  <p>As then I check</p>
  
  <pre><code>$ git branch -r -v
  origin/HEAD   -&gt; origin/master
  origin/master 7cf6ec5 test 02
  </code></pre>
  
  <p>that origin/master ref "7cf6ec5 test 02" is behind. The real origin/master is a "XXXXXX test 03".  <code>git fetch</code> only pulled the changes into FETCH_HEAD it didn't upload the local origin/master ref. What's the step for updating that ref?</p>
  
  <p>Note: </p>
  
  <pre><code>$ git fetch origin
  </code></pre>
  
  <p>Will get all remote refs and update them but unfortunately that's (a) a lot of clutter. (I don't want someone else's 30-50 random branches knowing that someone wouldn't want mine) and (b) as branches are deleted on origin those refs don't get deleted locally the next time I do <code>git fetch origin</code> which means that path ends up with cruft.</p>
  
  <p>The question is, how do fetch just one branch and update its ref locally?</p>