title: Finding the date/time a file appeared in a git branch
body: <p>How is possible to get the date in which a file appeared for the first time in a branch.</p>
  
  <p>Currently I'm using the following. The problem is that for merges it returns the creation date in the original branch instead of returning the date of the merge.</p>
  
  <p><code>
  $ git log --first-parent --format=%ct FILE
  </code></p>