Fix existing 'versions' not empty in the sandbox panel
When 'versions' is empty, the « From an existing version » option in the template is hidden. However reversed() returns an iterator, which is never False -> need to coerce versions into a list.
When 'versions' is empty, the « From an existing version » option in the template is hidden. However reversed() returns an iterator, which is never False -> need to coerce versions into a list.