CreateTransaction: Assume minimum p2sh-p2wpkh spend size for unknown change

test/functional/rpc_psbt.py

@@ -207,6 +207,10 @@ class PSBTTest(BitcoinTestFramework):
             assert tx_in["sequence"] > MAX_BIP125_RBF_SEQUENCE
         assert_equal(decoded_psbt["tx"]["locktime"], 0)
 
+        # Make sure change address wallet does not have P2SH innerscript access to results in success
+        # when attempting BnB coin selection
+        self.nodes[0].walletcreatefundedpsbt([], [{self.nodes[2].getnewaddress():unspent["amount"]+1}], block_height+2, {"changeAddress":self.nodes[1].getnewaddress()}, False)
+
         # Regression test for 14473 (mishandling of already-signed witness transaction):
         psbtx_info = self.nodes[0].walletcreatefundedpsbt([{"txid":unspent["txid"], "vout":unspent["vout"]}], [{self.nodes[2].getnewaddress():unspent["amount"]+1}])
         complete_psbt = self.nodes[0].walletprocesspsbt(psbtx_info["psbt"])