[repository] forbid usage of set_attributes() in before_add_entity
set_attributes() will generate a RQL query that will silently fail.
An explicit error is better.
You can still use the ``entity[attr] = value`` notation that
won't generate a SQL query but still update the inner state
of the entity and its edited_attributes attribute.
"""cube-specific forms/views/actions/components
:organization: Logilab
:copyright: 2001-2010 LOGILAB S.A. (Paris, FRANCE), license is LGPL v2.
:contact: http://www.logilab.fr/ -- mailto:contact@logilab.fr
:license: GNU Lesser General Public License, v2.1 - http://www.gnu.org/licenses
"""