title: Travis CI creates two builds for each Github commit push
body: <p>Each time I push to Github, it appears to trigger <em>two</em> Travis CI builds - one for the PR and one for the Push itself. They also appear to be separate builds, judging by the links.</p>
  
  <p>What's the exact difference between the two, and how can I enable it so that only one runs?</p>
  
  <p><a href="https://i.stack.imgur.com/iGfy0.png" rel="noreferrer"><img src="https://i.stack.imgur.com/iGfy0.png" alt="travis ci build"></a></p>