message: feat: shrink overflow check
diff: @@ -69,10 +69,7 @@ pub fn compact_to_target(compact: u32) -> (U256, bool) {
  ret <<= 8 * (exponent - 3);
  }
  - let overflow = !mantissa.is_zero()
  - && ((exponent > 34) // > (256 ** 31)
  - || (mantissa > U256::from(0xffu32) && exponent > 33)
  - || (mantissa > U256::from(0xffffu32) && exponent > 32));
  + let overflow = !mantissa.is_zero() && (exponent > 32);
  (ret, overflow)
  }
  @@ -211,6 +208,10 @@ mod tests {
  fn test_compact_overflowing2() {
  _test_compact_overflowing(U256::max_value());
  + let (_, overflow) = compact_to_target(0x21000001);
  + assert_eq!(overflow, true, "should overflow");
  + let (_, overflow) = compact_to_target(0x22000001);
  + assert_eq!(overflow, true, "should overflow");
  let (_, overflow) = compact_to_target(0x23000001);
  assert_eq!(overflow, true, "should overflow");
  }
  