title: Is it redundant in a Dockfile to run USER root since you're already root?
body: <p>Looking at <a href="https://github.com/sequenceiq/hadoop-docker/blob/master/Dockerfile" rel="noreferrer">this Dockerfile</a> it stars with:</p>
  
  <pre><code>FROM sequenceiq/pam:centos-6.5
  MAINTAINER SequenceIQ
  
  USER root
  </code></pre>
  
  <p>Now that seems redundant, since by default you'd already be <code>root</code>. But for argument's sake - let's look at the <a href="https://github.com/sequenceiq/docker-pam/blob/master/centos-6.5/Dockerfile" rel="noreferrer">parent Dockerfile</a>....that doesn't change the user. </p>
  
  <p>Now let's look at the grandparent Dockerfile. (It doesn't seem to be available). </p>
  
  <p>My question is: <strong>Is it redundant in a Dockfile to run USER root since you're already root?</strong></p>