old_contents: from __future__ import unicode_literals
  
  
  class AmavisRouter(object):
  
      """A router to control all database operations on models in
      the amavis application"""
  
      def db_for_read(self, model, **hints):
          """Point all operations on amavis models to 'amavis'."""
          if model._meta.app_label == 'modoboa_amavis':
              return 'amavis'
          return None
  
      def db_for_write(self, model, **hints):
          """Point all operations on amavis models to 'amavis'."""
          if model._meta.app_label == 'modoboa_amavis':
              return 'amavis'
          return None
  
      def allow_relation(self, obj1, obj2, **hints):
          """Allow any relation if a model in amavis is involved."""
          if obj1._meta.app_label == 'modoboa_amavis' \
             or obj2._meta.app_label == 'modoboa_amavis':
              return True
          return None
  
      def allow_migrate(self, db, app_label, model=None, **hints):
          """
          Make sure the auth app only appears in the 'amavis'
          database.
          """
          if db == "amavis":
              return app_label == "modoboa_amavis"
          return None
  
new_contents: from __future__ import unicode_literals
  
  
  class AmavisRouter(object):
  
      """A router to control all database operations on models in
      the amavis application"""
  
      def db_for_read(self, model, **hints):
          """Point all operations on amavis models to 'amavis'."""
          if model._meta.app_label == 'modoboa_amavis':
              return 'amavis'
          return None
  
      def db_for_write(self, model, **hints):
          """Point all operations on amavis models to 'amavis'."""
          if model._meta.app_label == 'modoboa_amavis':
              return 'amavis'
          return None
  
      def allow_relation(self, obj1, obj2, **hints):
          """Allow any relation if a model in amavis is involved."""
          if obj1._meta.app_label == 'modoboa_amavis' \
             or obj2._meta.app_label == 'modoboa_amavis':
              return True
          return None
  
      def allow_migrate(self, db, app_label, model=None, **hints):
          """
          Make sure the auth app only appears in the 'amavis'
          database.
          """
          if app_label == "modoboa_amavis":
              # modoboa_amavis migrations should be created in the amavis database.
              return (db == "amavis")
          elif db == "amavis":
              # Don't create non modoboa_amavis migrations in the amavis database.
              return False
          return None
  
subject: fix return value in allow_migrate()