title: Django bulk_create IntegrityError (Duplicate entry) with UUID primary_key
body: <p>I'm trying to save a huge amount of objects in a model, so I decided to use bulk_create by this way:</p>
  
  <pre><code>while True:
      batch = list(islice(records, 100))
      if not batch:
          break
      models.Record.objects.bulk_create(batch, batch_size)
  </code></pre>
  
  <p>But I get this error when I add the second batch of 100:</p>
  
  <pre><code>django.db.utils.IntegrityError: (1062, "Duplicate entry '165ab345f2ad47bbb2072ab7b3e8023f' for key 'PRIMARY'")
  </code></pre>
  
  <p>This is the model if it helps you:</p>
  
  <pre><code>class Record(models.Model):
      id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
      ...
  </code></pre>
  
  <p>Thanks in advance.</p>