Function forwards 

fn forwards(update: &SessionUpdate, watched: &[Subject], me: u64) -> bool

Whether this connection forwards one update.

A take’s own news reaches its connection whether or not the seat is showing. The reader may be on another seat while their recording runs, and the fold that draws the take - and the end settling it - is this connection’s: filtered by the watch, the record would go on drawing a recording that is over (#1880). Every other update keeps the watch rule alone.