partial backport of support for adbh's new interface to backup_command and restore_command
these methods can return lists or strings which are passed to subprocess.call
without or with the shell=True parameter respectively.
""" CW - nevow/twisted client
: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
"""