Accesscontrol

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- Avoid acquiring ``access`` from module wrapped by
``SecurityInfo._ModuleSecurityInfo``. See:
https://github.com/zopefoundation/AccessControl/issues/12

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- Harden test fix for machines that do not define `localhost`.

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- Test fix for machines that do not define `localhost`.

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- GitHub 6: Do not pass SecurityInfo instance itself to declarePublic/declarePrivate
when using the public/private decorator. This fixes ``Conflicting security declarations``
warnings on Zope startup.

- LP 1248529: Leave existing security manager in place inside
``RoleManager.manage_getUserRolesAndPermissions``.

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- LP 1169923: ensure initialization of shared ``ImplPython`` state
(used by ``ImplC``) when using the "C" security policy. Thanks to
Arnaud Fontaine for the patch.

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- Remove long-deprecated 'Shared' roles support (pre-dates Zope, never
used by Zope itself)

- Prevent infinite loop when looking up local roles in an acquisition chain
with cycles.