DOS a Plone site using folder default display

[neaj]

A client of mine just found a super-simple way to kill a Plone site:

• create a folder called 'somename',
• create a document in this folder called 'somename',
• select 'somename' as default view of the folder,
• delete the 'somename' document.

Now, if you view .../somename, Zope will spin and eventually take up all CPU. The folder tries to render the default view, which happens to be the same folder which tries to render the default view, which ...

The fix is probably to restrict the default view to parent[view], i.e. no acquisition.

[alecm]

This is worth fixing in 2.1 as well (especially as there seem to be some complaints on the lists).

[alecm]

(In [10369]) Made PloneTool.browserDefault check if the default page it is trying to render is the folder itself, and prevent it from doing so (which would cause an endless loop). Fixes #5704