Failling : dff7f55cd069a15493db00aef8f28f4f3be24b8f
Working : unknown
Updating the a scene (changing a scene setting) break the sequencer preview and make this scene render instead of the one specified in the Scene Strip.
In other words, the Scene strip preview always use the last updated scene.
Suprisingly, the render engine is always the one from the Scene Strip scene, even if another scene is rendered.