Rails routing gotcha: Don't name a route not_found

When moving our app to Bundler, I got the following error:

(__DELEGATE__):2:in `not_found': wrong number of arguments (2 for 0)
(ArgumentError)
from (__DELEGATE__):2:in `send'
from (__DELEGATE__):2:in `not_found'
from /app_dir/vendor/rails/activesupport/lib/active_support/
option_merger.rb:20:in `__send__'
from /app_dir/vendor/rails/activesupport/lib/active_support/
option_merger.rb:20:in `method_missing'
from /app_dir/config/routes/plaza_routes.rb:5
from /app_dir/vendor/rails/activesupport/lib/active_support/core_ext/
object/misc.rb:78:in `with_options'
from /app_dir/vendor/rails/actionpack/lib/action_controller/routing/
route_set.rb:51:in `namespace'

The secret was a route that looked like this:

global.not_found '/not_found', :controller => 'home', :action =>
'not_found'

The solution? Rename the route to something else. No idea why this wasn't exposed before, but at least there's a solution!