[2.4][Form][BC break?] error with CSRF protection disabled, but not for forms explicitly

The config

``` yaml
framework:
  csrf_protection: false
  form: ~
```

works fine with Symfony 2.0 - 2.3, but when upgrading to the master branch (currently commit dec28d19d6603d26055096d53e0f47c495eaea31), I get **LogicException: CSRF protection needs to be enabled in order to use CSRF protection for forms.**
