title: Specifying limit and offset in Django QuerySet wont work
body: <p>I'm using Django 1.6.5 and have MySQL's general-query-log on, so I can see the sql hitting MySQL.<br>
  And I noticed that Specifying a bigger limit in Django's QuerySet would not work:  </p>
  
  <pre><code>&gt;&gt;&gt; from blog.models import Author  
  &gt;&gt;&gt; len(Author.objects.filter(pk__gt=0)[0:999])
  &gt;&gt;&gt; len(Author.objects.all()[0:999])
  </code></pre>
  
  <p>And MySQL's general log showed that both query had <code>LIMIT 21</code>.  </p>
  
  <p>But a limit smaller than 21 would work, e.g. <code>len(Author.objects.all()[0:10])</code> would make a sql with <code>LIMIT 10</code>.</p>
  
  <p>Why is that? Is there something I need to configure?</p>