The current experimental builds (2.81.8) do not allow the creation of Rigid Body Constraints on Empties anymore.
Is that a purposeful move or an oversight? I use this for creating collider chains in conjunction with bones. It was still working in 2.81.2, so I am wondering why it is not anymore.
Broken: version: 2.81 (sub 8), branch: master, commit date: 2019-09-05 02:56, hash: rB6fc6f2504dfd
version: 2.80 (sub 74), branch: master, commit date: 2019-06-30 19:51, hash: rBbbb3500c9716