title: Get Jenkins Workspace Number
body: <p>if I am running concurrent Jenkins jobs, eg,</p>
  
  <pre><code>TestPipeline
  TestPipeline@2
  TestPipeline@3
  </code></pre>
  
  <p>How do I get the value of @2, @3, etc? Is there an env variable, or do I have to back it out from the path? It isn't <code>EXECUTOR_NUMBER</code>, which doesn't always match.</p>