Utility function taking care of the internal changes between RestrictedPython v3
and v5, keeping support for both (instead of having multiple if statements).

* Emtpy parameter.
* No argument.

Usually we run tests with two nodes, so when there's a conflict it's
always between the "main" node and the processing node, so we always
have a distributing node during conflict.

But when running with, for example, 2 nodes (the main node + 2 nodes),
the conflict might occur between the two processing nodes and after
the resolution we still don't have a distributing node.

When looking up a document by reference, using getDocumentValueList from
the context of a web site / web section might not find the documents,
depending on the predicates defined on the web site / web section.