title: Jenkins workflow environment variables causing a failure
body: <p>For this very simple workflow:</p>
  
  <pre><code>env.FOO = 42
  node {
    sh "echo $FOO"
  }
  </code></pre>
  
  <p>I get the following error: </p>
  
  <pre><code>Running: End of Workflow
  groovy.lang.MissingPropertyException: No such property: FOO for class: WorkflowScript
  </code></pre>
  
  <p>How do I access environment variables in workflow shell steps? </p>