title: Why does my git history look like a christmas tree?
body: <p>When doing <code>git log --decorate --oneline --graph</code> in one of our repositories shortly before Christmas, we found that the following structure had appeared (rotated to emphasize the tenuous festive theme):</p>
  
  <p><img src="https://i.stack.imgur.com/ZsXT6.png" alt="redacted git log output, rotated to look like a Christmas tree"></p>
  
  <p>How did this pattern in the commit graph arise?</p>
  
  <p><em>This is deliberately somewhat silly, of course, but there's a interesting point here — it's often difficult to see how to interpret particular patterns in the commit graph when you see them in you git history browser.</em></p>