title: Disable a stage in Jenkinsfile
body: <p>I want to temporary disable some stages in Jenkinsfile. Removing them and then restoring from version history seems like too much hasssle.
  I tried adding this:</p>
  <pre><code>    stage('Tests') {
        when {
          false
        }
      (...)
  </code></pre>
  <p>But results in an error when I trigger the job:</p>
  <pre><code>WorkflowScript: 30: Expected a when condition @ line 30, column 7.
  
           when {
  
           ^
  
  WorkflowScript: 30: Empty when closure, remove the property or add some content. @ line 30, column 7.
  
           when {
  </code></pre>
  <p>Is there a way to do <code>when: never</code> in Jenkins declarative pipelines?</p>