- Fix #54920
- ### Problem

  In #54845, I modified a call to `Record#create` for
  `Record#new` followed by `Record#save`. I didn't seen that the
  behaviour between both is different on associations.

  https://github.com/rails/rails/blob/b97917da8a801bf5360c3a9da913415bc8582735/activerecord/lib/active_record/associations/collection_association.rb#L355-L356

  ```ruby
  car = Car.new
  car.wheels.create # Check if `car` is persisted before creating a wheel.

  wheel = car.wheels.new
  wheel.save # Doesn't check if `car` is persisted
  ```

  ### Solution

  The original reason why I modified `#create` is because it doesn't
  allow to get the result of the transaction status within
  a nested transaction. The documentation explains it and mention
  to raise a rollback so that the outer transaction sees it but it misses
  an important detail: How to know whether the inner transaction was
  sucessfull since the Rollback error is silently swallowed.

  https://github.com/rails/rails/blob/b97917da8a801bf5360c3a9da913415bc8582735/activerecord/lib/active_record/transactions.rb#L159-L165

  A very simple example:

  ```ruby
  class Car < ApplicationRecord
    after_save do
      raise ActiveRecord::Rollback
    end
  end

  Car.transaction do
    car = Car.create!
    puts car.persisted? # Returns true. That's not correct.
  end
  ```

  The solution in this patch is to provide a flag on the record to know
  whether the last transaction was succesful.