/usr/lib/ruby/vendor_ruby/active_support/core_ext.rb is in ruby-activesupport 2:4.2.10-0ubuntu4.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 | Dir["#{File.dirname(__FILE__)}/core_ext/*.rb"].each do |path|
require path
end
|