          # Ignore validation if any field is None
          checked_values = [
              value for field, value in attrs.items() if field in self.fields
          ]
          if None not in checked_values and queryset.exists():
              field_names = ', '.join(self.fields)
              raise ValidationError(self.message.format(field_names=field_names))
  
      def __repr__(self):
          return unicode_to_repr('<%s(queryset=%s, fields=%s)>' % (
 
</s> remove         if queryset.exists():
 </s> add         if qs_exists(queryset): </s> remove         if queryset.exists():
 </s> add         if qs_exists(queryset): </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)
        if None not in checked_values and qs_exists(queryset):
          # Ignore validation if any field is None
          checked_values = [
              value for field, value in attrs.items() if field in self.fields
          ]
        if None not in checked_values and qs_exists(queryset):
              field_names = ', '.join(self.fields)
              raise ValidationError(self.message.format(field_names=field_names))
  
      def __repr__(self):
          return unicode_to_repr('<%s(queryset=%s, fields=%s)>' % (
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