message: fix up alpha_powers bug
diff: @@ -16,7 +16,7 @@ pub const CHACHA: Range<usize> = 58..(58+9);
  // TODO(mimoo): because of the way we do things, we never use alpha itself. This should instead return 1, alpha, alpha^2, etc. or better, an iterator
  pub fn alpha_powers<F: Field>(x: F) -> Vec<F> {
  let mut y = x;
  - (PSDN.start..MUL.end)
  + (PSDN.start..CHACHA.end)
  .map(|_| {
  y *= x;
  y
  