old_contents: from django.apps import AppConfig
  
  
  class PaymentConfig(AppConfig):
      name = 'apps.payment'
      verbose_name = 'Payment'
  
      def ready(self):
          super(PaymentConfig, self).ready()
  
          from reversion import revisions as reversion
  
          from apps.payment.models import PaymentPrice, PaymentTransaction
  
          reversion.register(PaymentPrice)
          reversion.register(PaymentTransaction)
  
new_contents: from django.apps import AppConfig
  
  
  class PaymentConfig(AppConfig):
      name = 'apps.payment'
      verbose_name = 'Payment'
  
      def ready(self):
          super(PaymentConfig, self).ready()
  
          from reversion import revisions as reversion
  
          from apps.payment.models import PaymentTransaction
  
          reversion.register(PaymentTransaction)
  
subject: Fix registering for already registered model