Do not un-mark fInMempool on wallet txn if ATMP fails.

Irrespective of the failure reason, un-marking fInMempool
out-of-order is incorrect - it should be unmarked when
TransactionRemovedFromMempool fires.

Author: TheBlueMatt

src/wallet/wallet.cpp

@@ -4114,18 +4114,13 @@ int CMerkleTx::GetBlocksToMaturity() const
 
 bool CWalletTx::AcceptToMemoryPool(const CAmount& nAbsurdFee, CValidationState& state)
 {
-    // Quick check to avoid re-setting fInMempool to false
-    if (mempool.exists(tx->GetHash())) {
-        return false;
-    }
-
     // We must set fInMempool here - while it will be re-set to true by the
     // entered-mempool callback, if we did not there would be a race where a
     // user could call sendmoney in a loop and hit spurious out of funds errors
     // because we think that the transaction they just generated's change is
     // unavailable as we're not yet aware its in mempool.
     bool ret = ::AcceptToMemoryPool(mempool, state, tx, nullptr /* pfMissingInputs */,
                                 nullptr /* plTxnReplaced */, false /* bypass_limits */, nAbsurdFee);
-    fInMempool = ret;
+    fInMempool |= ret;
     return ret;
 }