Rails: What gives date/datetime the (1i), (2i), etc values?

I can't seem to find how a date or datetime gets to have (1i), (2i), etc. What method gives this? I'm asking because I have a gem that breaks this functionality in Rails, and I want to make a test for it, and fix it.

This is the new error that happens when I install the gem:

undefined method `published_at(1i)=' for #<Page:0xc25ccd4> (NoMethodError)
./app/controllers/admin/pages_controller.rb:21:in `update'
./vendor/plugins/exception_notification/lib/exception_notifier.rb:19:in `call'
./features/step_definitions/web_steps.rb:29
./features/step_definitions/web_steps.rb:14:in `with_scope'
./features/step_definitions/web_s开发者_如何学运维teps.rb:28:in `/^(?:|I )press "([^"]*)"(?: within "([^"]*)")?$/'
features/domain_linking.feature:11:in `And I press "Update page"'

You'd need to take a look into the Rails source code, starting from ActionView::Helpers::DateHelper module and digging further in to get to the appropriate function.