title: Printing a zip from dictionary return Empty list
body: <p>I am performing this simple <code>zip</code> in python from a <code>dictionary</code> and I am not sure why the second time I do it it gives me an empty list.</p>
  <pre><code>l1= {'a':6, 'b':5, 'c':3, 'd':2, 'e':1, 'f':7, 'g':4, 'h':9}
  l2={'a':7, 'b':5, 'c':2, 'd':3, 'e':8}
  
  z=zip(l1.values(),l2.values())
  
  print(list(z)) #This gives me correct output.
  print(list(z)) #This gives me EMPTY list. WHY?
  
  [(6, 7), (5, 5), (3, 2), (2, 3), (1, 8)]
  []
  </code></pre>