plone/Products.Archetypes — comment on commit 38991095ea5d77df63ddb7b936af8eed7e359f45
File:  line 0
By davisagli:

This change breaks the labels for widgets that extend LabelWidget, CalendarWidget, SelectionWidget, or MutliSelectionWidget ... because they used to have their own names (so would get a label rendered in field.pt) but now they inherit render_own_label = True.

For backwards-compatibility we should do checks like, e.g. in CalendarWidget:
def render_own_label(self):
return bool(self.getName() == 'CalendarWidget')