title: How to use python 3 as a build script in non-python travis configuration?
body: <p>I'm trying to use <a href="https://travis-ci.org" rel="noreferrer">Travis CI</a> on a C library that uses custom python3-based build scripts.</p>
  
  <p>When the repository gets built, it fails on <code>./configure</code> because configure uses Python 3, which isn't installed by default.</p>
  
  <p>If I were building a Python project, I would use this in my <code>.travis.yml</code>:</p>
  
  <pre><code>python:
    - "3.4"
  </code></pre>
  
  <p>However, this doesn't seem to affect my repository because it is in C. (I tried running <code>which python3</code> and <code>python --version</code>, which reported that python 3 didn't exist and python 2.7 was in use instead.)</p>
  
  <p>The build script that I tried:</p>
  
  <pre><code>language: c
  
  python:
    - "3.4"
  </code></pre>
  
  <p>How can I have Python 3 available in Travis CI when my project is not a Python project?</p>