title: Pymongo cursor limit(1) returns more than 1 result
body: <p>These are all documents in my collection:</p>
  
  <pre><code>{
      "_id" : ObjectId("5110291e6ee1c31d5b275d01"),
      "d" : 24,
      "s" : [
          1,
          2,
          3
      ]
  }
  {
      "_id" : ObjectId("511029266ee1c31d5b275d02"),
      "d" : 24,
      "s" : [
          4,
          5,
          6
      ]
  }
  {
      "_id" : ObjectId("5110292e6ee1c31d5b275d03"),
      "d" : 24,
      "s" : [
          7,
          8
      ]
  }
  </code></pre>
  
  <p>This the query I want to run:</p>
  
  <pre><code>mongo = get_collection(self.collection_name)
  res = mongo.find().sort([('_id', -1)]).skip(1).limit(1)
  </code></pre>
  
  <p><code>get_collection()</code> is a helper method that I've made. Iterating over the cursor, <code>res</code>, produces only one document:</p>
  
  <pre><code>res = mongo.find().sort([('_id', -1)]).skip(1).limit(1)
  for document in res:
      print document
  
  &gt; {u's': [4.0, 5.0, 6.0], u'_id': ObjectId('511029266ee1c31d5b275d02'), u'd': 24.0}
  </code></pre>
  
  <p>However, accessing res using offsets returns two different documents for the 0th and 1st element:</p>
  
  <pre><code>res = mongo.find().sort([('_id', -1)]).skip(1).limit(1)
  pprint(res[0])
  &gt; {u'_id': ObjectId('511029266ee1c31d5b275d02'), u'd': 24.0, u's': [4.0, 5.0, 6.0]}
  pprint(res[1])
  &gt; {u'_id': ObjectId('5110291e6ee1c31d5b275d01'), u'd': 24.0, u's': [1.0, 2.0, 3.0]}
  </code></pre>
  
  <p>Is this a bug? <code>limit(1)</code> should only return one result, no? </p>