/usr/lib/ruby/1.8/mechanize/chain/ is in libwww-mechanize-ruby1.8 1.0.0-1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/1.8/mechanize/chain/auth_headers.rb
/usr/lib/ruby/1.8/mechanize/chain/body_decoding_handler.rb
/usr/lib/ruby/1.8/mechanize/chain/connection_resolver.rb
/usr/lib/ruby/1.8/mechanize/chain/custom_headers.rb
/usr/lib/ruby/1.8/mechanize/chain/handler.rb
/usr/lib/ruby/1.8/mechanize/chain/header_resolver.rb
/usr/lib/ruby/1.8/mechanize/chain/parameter_resolver.rb
/usr/lib/ruby/1.8/mechanize/chain/post_connect_hook.rb
/usr/lib/ruby/1.8/mechanize/chain/pre_connect_hook.rb
/usr/lib/ruby/1.8/mechanize/chain/request_resolver.rb
/usr/lib/ruby/1.8/mechanize/chain/response_body_parser.rb
/usr/lib/ruby/1.8/mechanize/chain/response_header_handler.rb
/usr/lib/ruby/1.8/mechanize/chain/response_reader.rb
/usr/lib/ruby/1.8/mechanize/chain/ssl_resolver.rb
/usr/lib/ruby/1.8/mechanize/chain/uri_resolver.rb