Binding doesn't restore when changing target

When changing the target of a Binding, the old target binding is not restored.
One would expect that if the Binding doesn't handle the old target anymore, it should restore it to how the target was before being handled (according to the restoreMode).

Attached is a code example reproducing the issue. The commented code is a workaround by abusing Behavior to disable and reenable the Binding on target change.