[devtools] Fix CubicWebTC.temporary_permissions
If the context manager is exited via an exception, the original
permissions should be restored.
# -*- coding: utf-8 -*-
# copyright %(year)s %(author)s, all rights reserved.
# contact %(author-web-site)s -- mailto:%(author-email)s
#
%(long-license)s
"""%(distname)s entity's classes"""