/usr/lib/ruby/vendor_ruby/active_support/core_ext/date/ is in ruby-activesupport 2:4.2.10-0ubuntu4.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/ruby/vendor_ruby/active_support/core_ext/date/acts_like.rb
/usr/lib/ruby/vendor_ruby/active_support/core_ext/date/calculations.rb
/usr/lib/ruby/vendor_ruby/active_support/core_ext/date/conversions.rb
/usr/lib/ruby/vendor_ruby/active_support/core_ext/date/zones.rb
/usr/lib/ruby/vendor_ruby/active_support/core_ext/date_and_time/calculations.rb
/usr/lib/ruby/vendor_ruby/active_support/core_ext/date_and_time/compatibility.rb
/usr/lib/ruby/vendor_ruby/active_support/core_ext/date_and_time/zones.rb
/usr/lib/ruby/vendor_ruby/active_support/core_ext/date_time/acts_like.rb
/usr/lib/ruby/vendor_ruby/active_support/core_ext/date_time/calculations.rb
/usr/lib/ruby/vendor_ruby/active_support/core_ext/date_time/compatibility.rb
/usr/lib/ruby/vendor_ruby/active_support/core_ext/date_time/conversions.rb
/usr/lib/ruby/vendor_ruby/active_support/core_ext/date_time/zones.rb