old_contents: from django.db import models
  from django.utils.translation import ugettext_lazy as _
  
  from yawf.config import INITIAL_STATE
  from yawf.base_model import WorkflowAwareModelBase
  
  
  class WorkflowAwareModel(WorkflowAwareModelBase):
  
      class Meta:
          abstract = True
  
      state = models.CharField(default=INITIAL_STATE,
              max_length=32, db_index=True, editable=False,
              verbose_name=_('state'))
  
new_contents: from django.db import models
  from django.utils.translation import ugettext_lazy as _
  
  from yawf.config import INITIAL_STATE
  from yawf.base_model import WorkflowAwareModelBase
  
  
  class WorkflowAwareModel(WorkflowAwareModelBase, models.Model):
  
      class Meta:
          abstract = True
  
      state = models.CharField(default=INITIAL_STATE,
              max_length=32, db_index=True, editable=False,
              verbose_name=_('state'))
  
subject: Add missing parent for WorkflowAwareModel