/usr/lib/ruby/vendor_ruby/active_support/core_ext/file.rb is in ruby-activesupport-3.2 3.2.6-6+deb7u1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 | require 'active_support/core_ext/file/atomic'
require 'active_support/core_ext/file/path'
|