title: Jenkins parameterized build not creating file
body: <p>Maybe I am misunderstanding the intended use for the Jenkins file parameter here...</p>
  
  <p>I want to be able to upload a file containing some data (in my case comma separated variables). I then want to simply read this file and do stuff with the data. I've got this setup using a Pipeline job.</p>
  
  <p>My file location is set to 'email_list.csv'. In my pipeline script I have</p>
  
  <pre><code>node {
    stage('post') {
      emailFile = readFile 'email_list.csv'
      println "${emailFile}"
      //.........
    }
  }
  </code></pre>
  
  <p>This fails with a <code>java.io.FileNotFoundException: /var/lib/jenkins/workspace/job-name/email_list.csv (No such file or directory)</code> exception</p>
  
  <p>Shouldn't the parameterized build have set up this file? If not, how do I read the data uploaded?</p>