cubicweb-container #3552734 rebuild container relation for top-less containers [validation pending]

Followup for

Now that we're able to build top-less containers (i.e. a subgraph of a container, with no container entity), it'd be nice if the container relation could be handled when the top-less container are later attached to the container.

Currently, the relation to the container is only added for the head entity of the top-less container, but not for its children.

done in2.7.0
load left0.000
closed by<not specified>
patchRebuild the container relation for subgraphs being attached to the container [rejected]