@Tobion I did change it (adding the `raw` prefix) in [here](https://github.com/symfony/symfony/commit/55014a6841bec50046e8329a4835c160ac31a496#L10R33) - I can't remember why, try to look at the tests.
More interesting might be the [original commit](https://github.com/symfony/symfony/commit/d17ba0e14775f6825b7df4a2d23c21036da06c11) where the decode was added.