Remove security proxy on item rename

This is needed because the IContainerItemRenamer from zope.copypastemove
is not correct registered and allows to rename on proxied items. 
We need to fix that later.

src/z3c/contents/browser.py

@@ -25,13 +25,14 @@
 from zope.copypastemove.interfaces import IPrincipalClipboard
 from zope.copypastemove.interfaces import IObjectCopier, IObjectMover
 from zope.copypastemove.interfaces import IContainerItemRenamer
-from zope.app.container.interfaces import IContainerNamesContainer
 from zope.exceptions import DuplicationError
 from zope.exceptions.interfaces import UserError
+from zope.security.proxy import removeSecurityProxy
 from zope.security.interfaces import Unauthorized
 from zope.traversing.interfaces import TraversalError
 from zope.traversing import api
 
+from zope.app.container.interfaces import IContainerNamesContainer
 from zope.app.container.interfaces import DuplicateIDError
 
 from z3c.form import button
@@ -346,7 +347,8 @@ def handlerRename(self, action):
                     newName = renameCol.getRenameValue(item)
                     if newName is not None and oldName != newName:
                         try:
-                            renamer = IContainerItemRenamer(self.context)
+                            container = removeSecurityProxy(self.context)
+                            renamer = IContainerItemRenamer(container)
                             renamer.renameItem(oldName, newName)
                             changed = True
                         except DuplicationError: