User.where(:id => [1,2]).where(:id => 2).arel.to_sql unexpected result

From rails console, running the following gives an unexpected result:

User.where(:id => [1,2]).where(:id => 2).arel.to_sql
 => "SELECT `users`.* FROM `users` WHERE (`users`.`id` IN (1, 2) OR `users`.`id` = 2)"

I'm not expecting that to be an OR.

This example is a very simplified example of a tableless User model I have that defines a method:

def cars
  Car.where(:id => list_of_users_car_ids_not_from_the_database)
end

where Cars are kept in the database. Then later in a controller

current_user.cars.find(params[:id])

(okay, this is also a simplified example, but much more representative of what I'm trying to accomplish)

Solution

These sources say it broke between 3.0.3 and 3.0.4, but they've 'fixed' it in 3.0.5.

They intentionally 'broke' it (they were fixing a bug and thought the new behavior was better). It should be reverted in 3.0.5, though.