title: Travis sudo is disabled
body: <p>I want to use <code>apt</code> to install some packages for the test, however, it fails due to that the sudo is disabled. I found the following in the test output: </p>
  
  <pre><code>Sudo, the FireFox addon, setuid and setgid have been disabled.
  </code></pre>
  
  <p>It seems that the output comes from <a href="https://github.com/travis-ci/travis-build/blob/master/lib/travis/build/script.rb#L151" rel="noreferrer">this line in travic-ci</a>, but setting <code>paranoid_mode</code> to false in <code>.travis.yml</code> does not work.</p>
  
  <p>How to enable sudo access?</p>
  
  <p>PS: I am using private repo.</p>
  
  <p>EDIT: The following <code>.travis.yml</code> will fail due to <code>sudo: must be setuid root</code> when running <code>sudo apt-get update -qq</code></p>
  
  <pre><code>language: python
  python:
    - "3.4"
  
  before_install:
    - sudo apt-get update -qq
  
  script:
    - nosetests
  </code></pre>
  
  <p>Setting <code>sudo: true</code> and/or <code>paranoid_mode: false</code> does not work.</p>