[entity] do not raise an AssertionError if the kwargs given to set_relations/attributes is empty
Regression was introduced in 3.16 with the new cw_set API.
Old set_relations and set_attributes methods did not crash on empty
kwargs.
Closes #3104019.
Document: cubicweb-doc
Title: CubicWeb documentation
Author: Logilab
Abstract: Some base documentation for CubicWeb users and developpers
Section: Apps/Programming
Format: HTML
Index: /usr/share/doc/cubicweb-documentation/index.html
Files: /usr/share/doc/cubicweb-documentation/*.html