[repository] fix edited_attributes management in multiple SET queries entity.edited_attributes was messed up with previous edited entities. The UpdateStep now gives a new fresh edited_attributes set to repository.glob_update_entity() so that each entity can modify it during its "transaction".

"""server side objects

: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
"""