  # We assume that 'validators' are intended for the child serializer,
  # rather than the parent serializer.
  MANY_RELATION_KWARGS = (
      'read_only', 'write_only', 'required', 'default', 'initial', 'source',
      'label', 'help_text', 'style', 'error_messages', 'allow_empty'
  )
  
  
  class RelatedField(Field):
      queryset = None
 
</s> remove         self.html_cutoff = kwargs.pop(
            'html_cutoff',
            self.html_cutoff or int(api_settings.HTML_SELECT_CUTOFF)
        )
 </s> add         cutoff_from_settings = api_settings.HTML_SELECT_CUTOFF
        if cutoff_from_settings is not None:
            cutoff_from_settings = int(cutoff_from_settings)
        self.html_cutoff = kwargs.pop('html_cutoff', cutoff_from_settings)
 </s> remove         self.html_cutoff = kwargs.pop(
            'html_cutoff',
            self.html_cutoff or int(api_settings.HTML_SELECT_CUTOFF)
        )
 </s> add         cutoff_from_settings = api_settings.HTML_SELECT_CUTOFF
        if cutoff_from_settings is not None:
            cutoff_from_settings = int(cutoff_from_settings)
        self.html_cutoff = kwargs.pop('html_cutoff', cutoff_from_settings)
 </s> remove from rest_framework import serializers
 </s> add from rest_framework import relations, serializers
    'label', 'help_text', 'style', 'error_messages', 'allow_empty',
    'html_cutoff', 'html_cutoff_text'
  # We assume that 'validators' are intended for the child serializer,
  # rather than the parent serializer.
  MANY_RELATION_KWARGS = (
      'read_only', 'write_only', 'required', 'default', 'initial', 'source',
    'label', 'help_text', 'style', 'error_messages', 'allow_empty',
    'html_cutoff', 'html_cutoff_text'
  )
  
  
  class RelatedField(Field):
      queryset = None
keep keep keep keep replace keep keep keep keep keep
 Add tests for HTML_CUTOFF setting and fix issue where setting it to None would raise an exception. 
rest_framework/relations.py