cubicweb #473924 copy action fails because of mandatory relations [rejected]

given the following schema:

class Suitcase(EntityType):
   name = String(required=True, maxsize=255, unique=True, fulltextindexed=True)

class Case(EntityType):
   name = String(required=True, maxsize=255, unique=True, fulltextindexed=True)
   in_suitcase = SubjectRelation('Suitcase', cardinality='1*',
                                composite='object', inlined=True)

If I try to copy an existing Case, this fails because the copy must be in_suitcase SomeSuitcase. However the form displayed to edit the copy does not allow me to set that relation, so I'm stuck.

prioritynormal
typebug
done in<not specified>
load0.000
load left0.000
closed by<not specified>