When the default for an element is asked, and the element is one in a
list, there are two options; a list can have a default value (like an
empty list), but its elements can have their own default values. This
change makes it so that if the current value of a list is its default,
it'll find the element in there. If the list is *not* the default, it'll
return the default for the element itself (i.e. an element has been
added to a list, but not all of the elements values have been set)