title: docker autobuild with git private submodule
body: <p>I have two private repositories on GitHub called <code>dashboard</code> and <code>ui</code>. I defined <code>ui</code> as a git submodule of <code>dashboard</code>, and I configured docker to autobuild <code>dashboard</code> on every changes on a specific branch.</p>
  
  <p>I read this documentation <a href="https://docs.docker.com/docker-hub/builds/">https://docs.docker.com/docker-hub/builds/</a>, but when I try to setup the deploy key given by docker in my <code>ui</code>'s settings, it says "Key already in use". Indeed, this key is already used by <code>dashboard</code> to allow docker to autobuild this repo!</p>
  
  <p>Here is my docker build log:</p>
  
  <blockquote>
    <p><strong>Error:</strong></p>
  
  <pre><code>Failed to clone repository: Cloning into '/tmp/build_byaxhis7sznbvmb6wgwzm6n'...
  Submodule 'app/styles/ui' (git@github.com:yllieth/ui.git) registered for path 'app/styles/ui'
  Cloning into 'app/styles/ui'...
  
  
  Warning: Permanently added 'github.com,192.30.252.130' (RSA) to the list of known hosts.
  ERROR: Repository not found.
  fatal: The remote end hung up unexpectedly
  Clone of 'git@github.com:yllieth/ui.git' into submodule path 'app/styles/ui' failed
  </code></pre>
    
    <p><strong>Dockerfile:</strong> None</p>
  </blockquote>
  
  <p>Docker doesn't find any Dockerfile even if I have one defined in my <code>dashboard</code> repo. So, I won't be able to give it any instructions or add another SSH key.</p>
  
  <p>If anyone has an idea about how using autobuild with private repos and git submodule, I'm interested!!</p>