Fix that CWallet::AbandonTransaction would only traverse one level

Prior to this change, it would mark only the first layer of
child transactions abandoned, due to always following the input hashTx
rather than the current now tx.

test/functional/wallet_abandonconflict.py

@@ -70,9 +70,17 @@ class AbandonConflictTest(BitcoinTestFramework):
         signed2 = self.nodes[0].signrawtransactionwithwallet(self.nodes[0].createrawtransaction(inputs, outputs))
         txABC2 = self.nodes[0].sendrawtransaction(signed2["hex"])
 
+        # Create a child tx spending ABC2
+        signed3_change = Decimal("24.999")
+        inputs = [ {"txid":txABC2, "vout":0} ]
+        outputs = { self.nodes[0].getnewaddress(): signed3_change }
+        signed3 = self.nodes[0].signrawtransactionwithwallet(self.nodes[0].createrawtransaction(inputs, outputs))
+        # note tx is never directly referenced, only abandoned as a child of the above
+        self.nodes[0].sendrawtransaction(signed3["hex"])
+
         # In mempool txs from self should increase balance from change
         newbalance = self.nodes[0].getbalance()
-        assert_equal(newbalance, balance - Decimal("30") + Decimal("24.9996"))
+        assert_equal(newbalance, balance - Decimal("30") + signed3_change)
         balance = newbalance
 
         # Restart the node with a higher min relay fee so the parent tx is no longer in mempool
@@ -87,7 +95,7 @@ class AbandonConflictTest(BitcoinTestFramework):
         # Not in mempool txs from self should only reduce balance
         # inputs are still spent, but change not received
         newbalance = self.nodes[0].getbalance()
-        assert_equal(newbalance, balance - Decimal("24.9996"))
+        assert_equal(newbalance, balance - signed3_change)
         # Unconfirmed received funds that are not in mempool, also shouldn't show
         # up in unconfirmed balance
         unconfbalance = self.nodes[0].getunconfirmedbalance() + self.nodes[0].getbalance()