`stream_with_context` does not propagate `g`

[npt]

When I use the stream_with_context decorator on a streaming generator, attributes set on the g object earlier in the request aren't visible in the generator. Someone else has described this already on stackoverflow and given an example.

This is easily worked around by passing the needed attributes into the generator and restoring them when it starts, but it's a surprising behavior that should be either changed or documented.