module ActiveSupport::Callbacks::ClassMethods

def reset_callbacks(name)
  callbacks = get_callbacks name
  ActiveSupport::DescendantsTracker.descendants(self).each do |target|
    chain = target.get_callbacks(name).dup
    callbacks.each { |c| chain.delete(c) }
    target.set_callbacks name, chain
  end
  self.set_callbacks name, callbacks.dup.clear
end