Comment 2 for bug 1403094

Janet, at first I thought that this error is entirely different from the one you're fixing. The reason is different error message "Could not process panel mypanel: type object 'PanelGroup' has no attribute 'panels'" - while your commit is fixing the situation with the error "Could not process panel foo: 'tuple' object has no attribute 'append'". After again looking at your fix I've realized that it's the same code, but it could use another check to eliminate this situation also. More comments in https://review.openstack.org/#/c/128133/

I agree that this one is duplicate.