Removed useless itertools.chain() call in ChoiceWidget.optgroups().
@@ -583,7 +583,7 @@ class ChoiceWidget(Widget):
groups = []
has_selected = False
- for index, (option_value, option_label) in enumerate(chain(self.choices)):
+ for index, (option_value, option_label) in enumerate(self.choices):
if option_value is None:
option_value = ''
