Add the name to the KeyError, to match the exception from pop().
@@ -152,7 +152,7 @@ class HolidayBase(dict):
def pop_named(self, name):
to_pop = [key for key in self if self[key] == name]
if not to_pop:
- raise KeyError
+ raise KeyError(name)
for key in to_pop:
self.pop(key)
