Comment 3 for bug 1836439

I wonder why we need to add in [1] when delete key. The function of func save_extra_specs is used to "Add or delete extra_specs", but it does add and delete extra_specs at one call. Also, I found it unnessary to do that, Should we recover its original function?
[1] https://github.com/openstack/nova/blob/master/nova/objects/flavor.py#L480