title: List comprehension with cursor from pymongo
body: <p>Here is my pymongo code:</p>
  
  <pre><code>client = MongoClient('localhost', 27017)
  db = client['somedb']
  collection = db.somecollection   
  return_obj = collection.find({"field1":"red"})
  
  #First print statement
  print([item['field1'] for item in return_obj])
  
  #Second print statement
  print([item['field1'] for item in return_obj])
  </code></pre>
  
  <p>The first print statement produces non-empty list, while the second one produces empty list. As if I have to reset an index on return_obj.</p>
  
  <p>Any ideas? </p>