This issue was found while using chameleon with plone.
There, folders have a folder_tabular_view, that uses a macro, and contains
fill-slot snippets that try to access the repeat variable from the macro.
That fails, debugging showed, that the repeat var is totally empty.
Assuming that code is specification and that this does not fail with zope stock
zpt implementation, I believe this to be a bug.
I attached a diff agains Chameleon that modifies an existing doctest, to trigger
the problematic behaviour.