Rails 3.0.8 and inflections

When updating my app to rails 3.0.8, only when I use the console I got the following situation:

"conta".pluralize => "contas"
"contas".singularize => "conta"

It's ok!

But, running a simple query:

Conta.first => ActiveRecord::StatementInvalid: Mysql2::Error: Table 'development.conta' doesn't exist: SELECT  `conta`.* FROM `conta` LIMIT 1

When set to an irregular inflection (and don't use singular/plural inflections), I have the same problem. Example:

ActiveSupport::Inflector.inflections do |inflect|
  inflect.irregular 'conta', 'contas'
  inflect.irregular 'Conta', 'Contas'
end

When the app is running (development environment), the same is not true. The problem is just in console and production environment.

Thanks!