Fallback to default_locale when locale was not specified

As today, i18n has this behavior:

I18n.locale
I18n.default_locale = :pt
I18n.locale #=> :en

I think that if the locale was not specified, #locale should return the default locale, do you agree?

For example, in a Rails application the default locale is specified the the config/application.rb file. Before loading this code, Rails loads the engines and one of the engines (rails_admin) executes I18n.locale, so the current default locale is cached to @locale and after overriding the default locale, #locale keeps returning the previous default locale, :en in this case.

What do you think?

`assert_nil  I18n.locale` here?