Use TAPROOT_ANNEX_PREFIX in sighash module

Author: dr-orlovsky

src/util/sighash.rs

@@ -27,7 +27,7 @@ use core::fmt;
 use core::ops::{Deref, DerefMut};
 use hashes::{sha256, sha256d, Hash};
 use io;
-use util::taproot::{TapLeafHash, TapSighashHash};
+use util::taproot::{TapLeafHash, TAPROOT_ANNEX_PREFIX, TapSighashHash};
 use SigHash;
 use {Script, Transaction, TxOut};
 
@@ -725,7 +725,7 @@ pub struct Annex<'a>(&'a [u8]);
 impl<'a> Annex<'a> {
     /// Creates a new `Annex` struct checking the first byte is `0x50`
     pub fn new(annex_bytes: &'a [u8]) -> Result<Self, Error> {
-        if annex_bytes.first() == Some(&0x50) {
+        if annex_bytes.first() == Some(&TAPROOT_ANNEX_PREFIX) {
             Ok(Annex(annex_bytes))
         } else {
             Err(Error::WrongAnnex)