cubicweb #3104019 calling set_relations() or set_attributes() yields an AssertionError [validation pending]

It used not to before 3.16.

Such an idiom seen in the wild, supposedly to wipe the relation cache.
We should probably not do anything.

prioritynormal
typebug
done in3.17.10
load0.100
load left0.000
closed by#c964d8cf6efc [entity] do not raise an AssertionError if the kwargs given to set_relations/attributes is empty
patch[entity] do not raise an AssertionError if the kwargs given to cw_set is empty [applied]