Missing helpers raises exception in Rails 1.2.2

If you're missing a default helper, in Rails 1.2.1 you'd get a warning
similar to "Missing default helper blah_helper.rb"

As of updating to Rails 1.2.2, I now get an exception trace, which
seems to point to a bug in the loader:

NoMethodError in SoftwareController#index

undefined method `is_missing?' for #<LoadError:0xb76e3054>

  vendor/rails/actionpack/lib/action_controller/helpers.rb:114:in
`default_helper_module!'
  vendor/rails/actionpack/lib/action_controller/helpers.rb:126:in
`inherited_without_api'
  vendor/rails/actionwebservice/lib/action_web_service/container/
action_controller_container.rb:84:in
`inherited_without_action_controller'
  vendor/rails/actionwebservice/lib/action_web_service/dispatcher/
action_controller_dispatcher.rb:32:in `inherited'
  app/controllers/software_controller.rb:1

Looks like LoadError is missing (ironically) is_missing?

-Nate