OrderedMultiSelectWidget can't handle single selection properly

# in advance, I apologize my rude english.

OrderedMultiSelectWidget.selected() doesn't seem to work properly.

below is an excerpt from 'itemswidget.py' in 'zope.app.form.browser' package
(cuurent revision of 'itemswidget.py' is 39064)

--
570 def selected(self):
571 """Return a list of tuples (text, value) that are selected."""
572 # Get form values
573 values = self._getFormValue()
574 # Not all content objects must necessarily support the attributes
575 if hasattr(self.context.context, self.context.__name__):
576 # merge in values from content
577 for value in self.context.get(self.context.context):
578 if value not in values:
579 values.append(value)
580
581 terms = [self.vocabulary.getTerm(value)
582 for value in values]
583 return [{'text': self.textForValue(term), 'value': term.token}
584 for term in terms]
--

if 'values' at 573 is a single value like 'abc' not a list,
the sigle value is shredded into meaningless values like 'a' or 'b'.
It results in an exception raised by getTerm() at 581.

I thik it would be a bug.

I'm totally newbie about python and zope3.
If it's not a bug, please forgive me.

regards.