          'invalid_choice': _('Select a valid choice. %(value)s is not one of the available choices.'),
      }
  
      def __init__(self, choices=(), required=True, widget=None, label=None,
                   initial=None, help_text=None, *args, **kwargs):
          super(ChoiceField, self).__init__(required=required, widget=widget, label=label,
                                          initial=initial, help_text=help_text, *args, **kwargs)
          self.choices = choices
  
      def __deepcopy__(self, memo):
 
</s> remove                  initial=None, help_text=None, *args, **kwargs):
 </s> add                  initial=None, help_text='', *args, **kwargs): </s> remove                  help_text=None, to_field_name=None, *args, **kwargs):
 </s> add                  help_text='', to_field_name=None, *args, **kwargs): </s> remove                  help_text=None, *args, **kwargs):
 </s> add                  help_text='', *args, **kwargs): </s> remove                  help_text=None, error_messages=None, show_hidden_initial=False,
 </s> add                  help_text='', error_messages=None, show_hidden_initial=False, </s> remove         if label is not None:
            label = smart_text(label)
 </s> add 
                 initial=None, help_text='', *args, **kwargs):
          'invalid_choice': _('Select a valid choice. %(value)s is not one of the available choices.'),
      }
  
      def __init__(self, choices=(), required=True, widget=None, label=None,
                 initial=None, help_text='', *args, **kwargs):
          super(ChoiceField, self).__init__(required=required, widget=widget, label=label,
                                          initial=initial, help_text=help_text, *args, **kwargs)
          self.choices = choices
  
      def __deepcopy__(self, memo):
keep keep keep keep replace keep keep keep keep keep
 Removed forced typecasting of help_text/label Field arguments

In any case, setting those variables to non-ascii utf-8 bytestrings
is now considered a programming error. 
django/forms/fields.py