title: "Peer's Certificate issuer is not recognized" while adding docker repo
body: <p>Running:</p>
  
  <pre><code>yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo
  </code></pre>
  
  <p>Produces:</p>
  
  <pre><code>Could not fetch/save url https://download.docker.com/linux/centos/docker-ce.repo to file /etc/yum.repos.d/docker-ce.repo:
  [Errno 14] curl#60 - "Peer's Certificate issuer is not recognized."
  </code></pre>