fix #4236

lib/transaction.py

@@ -805,18 +805,17 @@ class Transaction:
 
     @classmethod
     def get_preimage_script(self, txin):
-        # only for non-segwit
+        pubkeys, x_pubkeys = self.get_sorted_pubkeys(txin)
         if txin['type'] == 'p2pkh':
             return bitcoin.address_to_script(txin['address'])
         elif txin['type'] in ['p2sh', 'p2wsh', 'p2wsh-p2sh']:
-            pubkeys, x_pubkeys = self.get_sorted_pubkeys(txin)
             return multisig_script(pubkeys, txin['num_sig'])
         elif txin['type'] in ['p2wpkh', 'p2wpkh-p2sh']:
-            pubkey = txin['pubkeys'][0]
+            pubkey = pubkeys[0]
             pkh = bh2u(bitcoin.hash_160(bfh(pubkey)))
             return '76a9' + push_script(pkh) + '88ac'
         elif txin['type'] == 'p2pk':
-            pubkey = txin['pubkeys'][0]
+            pubkey = pubkeys[0]
             return bitcoin.public_key_to_p2pk_script(pubkey)
         else:
             raise TypeError('Unknown txin type', txin['type'])