Function no_snapshot 

fn no_snapshot(result: &Submitted, facts: Option<&DerivedFacts>) -> bool

§12 step 6 (C18): a transaction that got past step 5 (it ran, or waits for its activation window) with UserData among its sensitivities, where snapshots are unsupported (always, in Phase A: no snapshot backend is wired), logs NoSnapshot and continues.