message: Declare bw ascii unreachable instead of simple panic
diff: @@ -680,7 +680,7 @@ impl Sample for BWBit {
  _height: u32,
  _samples: u32,
  ) -> ImageResult<Vec<Self::T>> {
  - panic!("BW bits from anymaps are never encoded as ascii")
  + unreachable!("BW bits from anymaps are never encoded as ascii")
  }
  }
  