Bone constraints per armature, not per object


I have some armature objects using the same armature. I’ve changed the bone constraints of one of them. Later, the other ones were still behaving strangely. After a long search, I’ve seen that the bone constraints are on a per-object basis. This normally does not make sense to me because it’s the same skeleton with the same freedom of rotation, whereas it does make sense to pose the instances individually.

How can I make one armature only have one set of constraints? I don’t want to copy all changes.