  from __future__ import unicode_literals
  
  from django.apps import apps
  
  from .. import Warning, register
  
  
  @register('compatibility')
  def check_1_6_compatibility(**kwargs):
      errors = []
 
</s> remove @register('compatibility')
 </s> add @register(Tags.compatibility) </s> remove from . import Error, register
 </s> add from . import Error, Tags, register </s> remove from .registry import register, run_checks, tag_exists
 </s> add from .registry import register, run_checks, tag_exists, Tags </s> remove @register('models')
 </s> add @register(Tags.models)
from .. import Warning, register, Tags
  from __future__ import unicode_literals
  
  from django.apps import apps
  
from .. import Warning, register, Tags
  
  
  @register('compatibility')
  def check_1_6_compatibility(**kwargs):
      errors = []
keep keep keep keep replace keep keep keep keep keep
 Fixed #22195 -- Used constants to define built-in tags for check framework.

Thanks Elvard for the patch. 
django/core/checks/compatibility/django_1_6_0.py