ComputedAttribute permission problems in 2.7

[richard]

ComputedAttributes sometimes run afoul in the permission machinery with the following sort of error (courtesy VerboseSecurity):

"""
Module Products.PageTemplates.Expressions, line 336, in restrictedTraverse
   - __traceback_info__: {'path': ['cgpublisher_url'], 'TraversalRequestNameStack': [], 'page_layout': <CG TemplatedHTML page_layout at 0x3b5de00>}
  Module AccessControl.ImplPython, line 404, in validate
  Module Products.VerboseSecurity.VerboseSecurityPolicy, line 101, in validate
Unauthorized: No container provided. Access to 'cgpublisher_url' of None, acquired through (CG WebSpace web at 0x3b5d9c0), denied.
"""

Where "cgpublisher_url" is the ComputedAttribute.

[Andreas Jung (ajung)]

Please describe how to reproduce the error.

[Florent Guillaume (efge)]

Please provide some code to reproduce the problem othewise the bug will be rejected for lack of activity.

[Colin Watson (cjwatson)]

The zope2 project on Launchpad has been archived at the request of the Zope developers (see https://answers.launchpad.net/launchpad/+question/683589 and https://answers.launchpad.net/launchpad/+question/685285). If this bug is still relevant, please refile it at https://github.com/zopefoundation/zope2.