          filter_kwargs[self.field_name] = value
          filter_kwargs['%s__day' % self.date_field_name] = date.day
          filter_kwargs['%s__month' % self.date_field_name] = date.month
          filter_kwargs['%s__year' % self.date_field_name] = date.year
          return queryset.filter(**filter_kwargs)
  
  
  class UniqueForMonthValidator(BaseUniqueForValidator):
      message = _('This field must be unique for the "{date_field}" month.')
  
 
</s> remove         return queryset.filter(**filter_kwargs)
 </s> add         return qs_filter(queryset, **filter_kwargs) </s> remove         return queryset.filter(**filter_kwargs)
 </s> add         return qs_filter(queryset, **filter_kwargs) </s> remove         if queryset.exists():
 </s> add         if qs_exists(queryset): </s> remove         if None not in checked_values and queryset.exists():
 </s> add         if None not in checked_values and qs_exists(queryset): </s> remove         if queryset.exists():
 </s> add         if qs_exists(queryset):
        return qs_filter(queryset, **filter_kwargs)
          filter_kwargs[self.field_name] = value
          filter_kwargs['%s__day' % self.date_field_name] = date.day
          filter_kwargs['%s__month' % self.date_field_name] = date.month
          filter_kwargs['%s__year' % self.date_field_name] = date.year
        return qs_filter(queryset, **filter_kwargs)
  
  
  class UniqueForMonthValidator(BaseUniqueForValidator):
      message = _('This field must be unique for the "{date_field}" month.')
  
keep keep keep keep replace keep keep keep keep keep
 Robust uniqueness checks. (#4217)

* Robust uniqueness checks
* Add master to test matrix (allow_failures) 
rest_framework/validators.py