error[E0277]: the trait bound `One: From<Two>` is not satisfied
  --> $DIR/no_handle_conversions_require_into_fail.rs:11:18
   |
11 |     Two --(B)--> One;
   |                  ^^^ the trait `From<Two>` is not implemented for `One`
   |
   = note: required because of the requirements on the impl of `Into<One>` for `Two`
   = note: required by `TransitionResult::<Sm, Ds>::from`