title: What does "Client failed to connect to the D-BUS daemon" mean?
body: <p>I am using a very complex setup to test various non-public webpages. I use <code>jenkins</code> to run the <code>python-selenium</code> tests within a <code>docker</code>image. That way, I am completely independent of the jenkins environment and can create my own environment. In this environment I have the following software installed:</p>
  
  <ul>
  <li>Ubuntu 16.04.3</li>
  <li>Firefox: Mozilla Firefox 57.0.1</li>
  <li>geckodriver: 0.18.0</li>
  <li>nosetests: 1.3.7</li>
  <li>selenium: 3.8.0</li>
  </ul>
  
  <p>When running the tests, which mostly succeed, I see in the <code>geckodriver.log</code> output messages like</p>
  
  <pre><code>(firefox:55): GConf-WARNING **: Client failed to connect to the D-BUS daemon:
  /usr/bin/dbus-launch terminated abnormally without any error message
  </code></pre>
  
  <p>My questions: </p>
  
  <ul>
  <li>What does this message mean?</li>
  <li>Could that be an indication of the reason why sometimes the tests are failing? </li>
  <li>If so, how to fix it?</li>
  </ul>