title: User can't git submodule update, but they can pull from all submodules independantly
body: <p>I have a new team member who gets a Permission Error when trying to perform their initial <code>git submodule update</code>:</p>
  
  <pre><code>[mrTeamMember@desktop application]$ git submodule update
  Initialized empty Git repository in /home/mrTeamMember/work/application/subMod/.git/
  mrTeamMember@server.example.com's password: 
  Permission denied, please try again.
  </code></pre>
  
  <p>If, however, they simply <code>git pull</code> from the submodules' repositories directly, they get no error!</p>
  
  <p>How can this be?</p>
  
  <p>What could be causing this problem?</p>