title: Django annotate count doesn't work always return 1
body: <p>My models:</p>
  
  <pre><code>class PicKeyword(models.Model):
      """chat context collection
  
      """
      keyword = models.TextField(blank=True, null=True)
  </code></pre>
  
  <p>Myfilter:</p>
  
  <pre><code>from django.db.models import Count
  PicKeyword.objects.annotate(Count('keyword'))[0].keyword__count
  </code></pre>
  
  <p>The result always get 1</p>
  
  <p>just like:</p>
  
  <pre><code>print(PicKeyword.objects.filter(keyword='hi').count()
  </code></pre>
  
  <p>show:
      3</p>
  
  <pre><code>PicKeyword.objects.filter(keyword='hi').annotate(Count('keyword'))[0].keyword__count
  </code></pre>
  
  <p>show:
      1</p>
  
  <p>Is it because I use sqllite or my keyword type is Textfield?</p>