title: cursor bug with limit in pymongo?
body: <p>I have a collection with 5 rows, but I need to select one:</p>
  
  <pre><code>for row in db.foo.find({},{"_id":1}).limit(1).sort("_id",-1):print row
  </code></pre>
  
  <p>result:</p>
  
  <pre><code>{u'_id': 4}
  </code></pre>
  
  <p>but, when count cursor</p>
  
  <pre><code>flag=db.foo.find({},{"_id":1},limit=1).sort("_id",-1)
  print flag.count()
  </code></pre>
  
  <p>result=5</p>
  
  <p>and <code>flag=db.foo.find({},{"_id":1},limit=1).sort("_id",-1).count()</code> result: 5</p>
  
  <p>anyone has idea why this happens?</p>
  
  <p>MongoDB shell version: 2.4.4</p>
  
  <blockquote>
    <blockquote>
      <blockquote>
        <p>pymongo.version
        '2.5.1+'</p>
      </blockquote>
    </blockquote>
  </blockquote>