title: pymongo sort and find_one issue
body: <p>I am trying to sort a collection called <code>user_score</code> using the key <code>position</code> and get the very first document of the result. In this case the collection <code>user_score</code> doesn't exist and I was hoping to get the result as <code>None</code>, but i was getting a cursor back.</p>
  
  <p>1.
  result =</p>
  
  <pre><code>db.user_score.find({'score':'$lt':score}}).sort("position,pymongo.DESCENDING").limit(1)
  </code></pre>
  
  <p>Now i changed my query like below and did not get anything as expected.</p>
  
  <p>2.
  result = </p>
  
  <pre><code>db.user_score.find_one({'score':{'$lt':score}}, sort=[("position", pymongo.DESCENDING)])
  </code></pre>
  
  <p>What's the problem with my first query? </p>
  
  <p>Thanks</p>