bugfix: move zero bits append in mint contract

src/circuit/mint_contract.rs

@@ -125,6 +125,9 @@ impl Circuit<bls12_381::Scalar> for MintContract {
         // Line 60: binary_extend preimage value
         preimage.extend(value);
 
+        // Line 99: binary_extend preimage asset_id
+        preimage.extend(asset_id);
+
         // add 4 zero bits
         for _ in 0..4 {
             // Line 71: alloc_const_bit zero_bit false
@@ -133,8 +136,6 @@ impl Circuit<bls12_381::Scalar> for MintContract {
             // Line 72: binary_push preimage zero_bit
             preimage.push(zero_bit);
         }
-        // Line 99: binary_extend preimage asset_id
-        preimage.extend(asset_id);
 
         // Line 67: binary_extend preimage serial
         preimage.extend(serial);
@@ -147,6 +148,7 @@ impl Circuit<bls12_381::Scalar> for MintContract {
             // Line 72: binary_push preimage zero_bit
             preimage.push(zero_bit);
         }
+
         // Line 83: binary_extend preimage randomness_coin
         preimage.extend(randomness_coin);