title: CodeCommit fast-forward merge
body: <p>I'm trying to merge a pull request using fast-forward merge in the CodeCommit but the fast-forward merge option is disabled.</p>
  <p>Any idea why?</p>
  <p><a href="https://i.stack.imgur.com/ga5IL.png" rel="nofollow noreferrer">codecommit merge pull request</a></p>