CircleCI 2.0 SSH debug: Failed to enable SSH, No SSH key is found : <p>Config:</p>

<ul>
<li>CircleCI 2.0</li>
<li>Bitbucket private repo</li>
</ul>

<p>After I click on "Rebuild with SSH", the "Enable SSH" section outputs</p>

<blockquote>
  <p>Failed to enable SSH
  No SSH key is found. Please make sure you've
  added at least one SSH key in your VCS account.</p>
</blockquote>

<p>What does this mean? How do I fix this?</p>
