/usr/lib/ruby/vendor_ruby/active_support/core_ext.rb is in ruby-activesupport-3.2 3.2.16-2.
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"].sort.each do |path|
require "active_support/core_ext/#{File.basename(path, '.rb')}"
end
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