module ActiveSupport::Callbacks::ClassMethods

def reset_callbacks(symbol)
  callbacks = send("_#{symbol}_callbacks")
  ActiveSupport::DescendantsTracker.descendants(self).each do |target|
    chain = target.send("_#{symbol}_callbacks").dup
    callbacks.each { |c| chain.delete(c) }
    target.send("_#{symbol}_callbacks=", chain)
    target.__reset_runner(symbol)
  end
  self.send("_#{symbol}_callbacks=", callbacks.dup.clear)
  __reset_runner(symbol)
end