Option to split small chains instead of putting on single new line

My max_width is 80, using stable version of rustfmt.

E.g. this code I would expect to remain as is:

    let resp = req
        .state()
        .db
        .send(msg)
        .from_err()
        .and_then(|db_resp| match db_resp {
            Ok(roles) => Ok(HttpResponse::Created().json(roles)),
            Err(e) => Err(e),
        });

but is instead formatted like this:

    let resp =
        req.state()
            .db
            .send(msg)
            .from_err()
            .and_then(|db_resp| match db_resp {
                Ok(roles) => Ok(HttpResponse::Created().json(roles)),
                Err(e) => Err(e),
            });

Smaller chains are sometimes kept as a single line but put on a new line, like so:

                let login_ids: Vec<_> =
                    result.active_members.iter().map(|m| m.login_id).collect();

It would be great to have an option to specify that I prefer splitting up such chains instead of keeping them together as much as possible. Apologies if there is already an option for this and I've missed it.

No source files or tests are named. Reproduce the two formatting examples with rustfmt using max_width 80, then trace the formatting behavior and option configuration; done means a documented option consistently prefers splitting small chains instead of moving the whole chain to a new line.