Fix atomic beef

Author: shruggr

transaction/beef.go

@@ -103,8 +103,6 @@ func readBeefTx(reader *bytes.Reader, BUMPs []*MerklePath) (*map[string]*BeefTx,
 				sourceTxid := input.SourceTXID.String()
 				if sourceObj, ok := txs[sourceTxid]; ok {
 					input.SourceTransaction = sourceObj.Transaction
-				} else if beefTx.Transaction.MerklePath == nil && beefTx.KnownTxID == nil {
-					return nil, fmt.Errorf("reference to unknown txid in bump: %s", sourceTxid)
 				}
 			}
 
@@ -118,12 +116,20 @@ func readBeefTx(reader *bytes.Reader, BUMPs []*MerklePath) (*map[string]*BeefTx,
 
 func NewBeefFromBytes(beef []byte) (*Beef, error) {
 	reader := bytes.NewReader(beef)
-
 	version, err := readVersion(reader)
 	if err != nil {
 		return nil, err
 	}
 
+	if version == ATOMIC_BEEF {
+		txid := make([]byte, 32)
+		if _, err = reader.Read(txid); err != nil {
+			return nil, err
+		} else if version, err = readVersion(reader); err != nil {
+			return nil, err
+		}
+	}
+
 	if version == BEEF_V1 {
 		BUMPs, err := readBUMPs(reader)
 		if err != nil {