title: Access Stage name during the build in Jenkins pipeline
body: <p>Let's say we have the following <code>Jenkinsfile</code>:</p>
  
  <pre><code>stage name: "Cool stage"
      sh 'whoami'
  stage name: "Better stage"
      def current_stage = getCurrentStageName()
      echo "CONGRATULATIONS, you are on stage: $current_stage"
  </code></pre>
  
  <p>The question is how to implement <strong><code>getCurrentStageName()</code></strong>. I know, that I can get an access to build run-time using <code>currentBuild.rawBuild</code>.
  But how to get stage name from that point?</p>
  
  <p>I need this for some customization in email notifications, so that I can always catch failed stage name and include it into email body.</p>