message: Fix parsing of rseed in parse_note_plaintext_without_memo() and try_sapling_output_recovery()
diff: @@ -359,11 +359,12 @@ fn parse_note_plaintext_without_memo<P: consensus::Parameters>(
  let v = (&plaintext[12..20]).read_u64::<LittleEndian>().ok()?;
  - let mut r = [0u8; 32];
  - r.copy_from_slice(&plaintext[20..COMPACT_NOTE_SIZE]);
  + let r: [u8; 32] = plaintext[20..COMPACT_NOTE_SIZE]
  + .try_into()
  + .expect("slice is the correct length");
  let rseed = if plaintext[0] == 0x01 {
  - let rcm = Fs::from_repr(FsRepr(r.try_into().expect("slice is the correct length")))?;
  + let rcm = Fs::from_repr(FsRepr(r))?;
  Rseed::BeforeZip212(rcm)
  } else {
  Rseed::AfterZip212(r)
  @@ -550,11 +551,12 @@ pub fn try_sapling_output_recovery<P: consensus::Parameters>(
  let v = (&plaintext[12..20]).read_u64::<LittleEndian>().ok()?;
  - let mut r = [0u8; 32];
  - r.copy_from_slice(&plaintext[20..COMPACT_NOTE_SIZE]);
  + let r: [u8; 32] = plaintext[20..COMPACT_NOTE_SIZE]
  + .try_into()
  + .expect("slice is the correct length");
  let rseed = if plaintext[0] == 0x01 {
  - let rcm = Fs::from_repr(FsRepr(r.try_into().expect("slice is the correct length")))?;
  + let rcm = Fs::from_repr(FsRepr(r))?;
  Rseed::BeforeZip212(rcm)
  } else {
  Rseed::AfterZip212(r)
  