4.3.x Incomplete, discussion wanted: Fix for Site Error when pasting deleted item.

This should fix https://dev.plone.org/ticket/13577. Raised CopyErrors are caught and now give an error in the portal message.

At the moment all CopyErrors are caught, not just eNotFound. This is undesirable, so i'd like to get the reason for the exception from e.

However, it seems to be impossible for a normal user to look into the error from a controller script: trying to get e.message yields Unauthorized. Is there a way around that? A helper view which reads the error is the only thing i can think of...