title: Indexing does not work when using postgres with Django
body: <p>So, the issue is pretty simple but I couldn't find any info related to it</p>
  
  <pre><code>&gt;&gt;&gt; Match.objects.all()[0].team_set.all()
  &lt;QuerySet [&lt;Team: EG&gt;, &lt;Team: Liquid&gt;]&gt;
  &gt;&gt;&gt; Match.objects.all()[0].team_set.all()[1:2]
  &lt;QuerySet [&lt;Team: Liquid&gt;]&gt;
  &gt;&gt;&gt; Match.objects.all()[0].team_set.all()[0:1]
  &lt;QuerySet [&lt;Team: Liquid&gt;]&gt;
  &gt;&gt;&gt; Match.objects.all()[0].team_set.all()[0]
  &lt;Team: Liquid&gt;
  &gt;&gt;&gt; Match.objects.all()[0].team_set.all()[1]
  &lt;Team: Liquid&gt;
  </code></pre>
  
  <p>Basically it refuses to give me ForeignKey object by its index. Any ideas?</p>