title: Union Linq method not working
body: <p>I have two Ienumerable</p>
  
  <pre><code>IEnumerable&lt;int&gt; a = Enumerable.Range(5,5); // 5,6,7,8,9
  IEnumerable&lt;int&gt; b = Enumerable(){2,3}; // 3
  
  var c = a.Union(b)
  
  c should be 2,3,5,6,7,8,9 but I only get 5,6,7,8,9
  </code></pre>
  
  <p>I just need the two of them joined.</p>