Annotations are duplicated when undecorating a tracked nonterminal tree

[krame505]

Something I don't understand in the origin tracking implementation: when a tracked tree gets explicitly undecorated with new, we deep-copy the children in order to set their origins info to indicate that they were also undecorated by new. But for some reason we are also deep-copying and updating the origin of annotations (any that are tracked nonterminals, at least) even though they are not undecorated when the tree is undecorated.

This also seems to be inconsistent with the origin tracking paper, which only mentions children being duplicated. So I am I right in thinking that this is a bug, or was there some implementation reason for this that I'm not aware of?

In practice I don't think this is exercised anywhere, since having a tracked nonterminal as an annotation on another tracked nonterminal is kind of a weird thing to do.