title: CloudFormation Join in Tags
body: <p>I'm running a CloudFormation template that uses the following snippet to tag various resources (this is a ELB tag, but others also exhibit this problem) I would expect this to produce a name tag of <code>stackName-asgElb</code> but it actually produces names such as <code>olive-asg-asgElb-16GSCPHUFSWEN</code>. </p>
  
  <p>The stack name in this case was named <code>olive-asg</code> so I was expecting <code>olive-asg-asgElb</code>, without the <code>-16GSCPHUFSWEN</code> on the end.</p>
  
  <p>Does anybody know where the seemingly random string on the end comes from?</p>
  
  <p><em>CF template snippet</em>:</p>
  
  <pre><code>Tags: [
      {
          Key: "Name",
          Value: {
              "Fn::Join": [
                  "-",
                  [
                      {
                          Ref: "AWS::StackName"
                      },
                      "asgElb"
                  ]
              ]
          }
      }
  ]
  </code></pre>