cubicweb-container #3515377 [utils.needed_etype] unroll all rdefs, following yams warning [validation pending]

Since yams 0.38, calling eschema.rdef(rtype, role) for a non-attribute will complain if there are actually several possible targets.

In this case, we should indeed check all the rdefs.

prioritynormal
typeenhancement
done in2.7.0
load0.100
load left0.000
closed by#8f804ee46af4 Switch to rdefs to define the container structure, and make the container relation reflexive
patch[utils] needed_etypes: unroll all the rdefs rather than peeking at the first [rejected]Switch to rdefs to define the container structure, and make the container relation reflexive [applied]