validate :updatable? # First validation there is
with_options :if => Proc.new { |object| object.errors.empty? } do |updatable|
updatable.with_options :if => \
You are right that when nesting two :if conditions, the inner one will replace the outer one and always be checked. A workaround to handle two levels of nesting is:
with_options :unless => !(outer condition) do
with_options :if => (inner condition) do
The if and unless conditions do not overwrite each other. I'm not sure I would call this a bug, but it would be nice if you could nest multiple :if conditions.