Two different forms of `include` in Ruby, only one of which works as expected

rails_version.rb

class BustedInclude
  include ActiveModel::Validations, ActiveModel::Validations::Callbacks
  before_validation { puts 'Callback!' }
end

# outputs only `true`
instance = BustedInclude.new
instance.valid?

class WorkingInclude
  include ActiveModel::Validations
  include ActiveModel::Validations::Callbacks
  before_validation { puts 'Callback!' }
end

# outputs "Callback!" and then `true`
instance = WorkingInclude.new
instance.valid?