title: How to access model's class level variable in data migration?
body: <p>Here is my model.</p>
  
  <pre><code>Poll(models.Model):
     title = models.CharField(max_length=1024)
     MY_VAR = ['my_class_level_attribute'] # I want to access this
  </code></pre>
  
  <p>Here is my data migration:</p>
  
  <pre><code>def my_func(apps, schema_editor):
      Poll = apps.get_model('my_app', 'Poll')
      print Poll.MY_VAR
  
  
  class Migration(migrations.Migration):
  
      dependencies = [
          ('webmerge', '0012_previous_migration'),
      ]
  
      operations = [
          migrations.RunPython(my_func)
      ]
  </code></pre>
  
  <p>The line <code>print Poll.MY_VAR</code> gives an attribute error. I think the issue might is in how <code>get_model</code> performs within a data migration because the following lines succeed in a Django shell:</p>
  
  <pre><code>In [2]: from django.apps import apps
  In [3]: Poll = apps.get_model('my_app', 'Poll')
  In [4]: Poll.MY_VAR
  Out[4]:  ['my_class_level_attribute']
  </code></pre>