If I create an RBF transaction using the Qt GUI but specify my own custom change address, bumpfee doesn't work because it claims it can't find the change address:

    "Transaction does not have a change output"

This is because none of the outputs satisfy

    pWallet->IsChange(...)

I see there's a "TODO" commented in `CWallet::IsChange()` in `src/wallet/wallet.cpp`:

    // TODO: fix handling of 'change' outputs. The assumption is that any
    // payment to a script that is ours, but is not in the address book
    // is change.

I tend to put all my addresses in the address book whether I'm going to use them as change or not. I guess if the wallet was capable of creating its own SegWit change addresses I'd stop using custom change addresses, but currently it always seems to send change to a legacy address if I don't manually specify a change address.
new_outputs_value += output.nValue;
    }
    
    if (recipients.empty()) {
        
        if (std::get_if<CNoDestination>(&new_coin_control.destChange)) {
            errors.emplace_back(Untranslated("Unable to create transaction. Transaction must have at least one recipient"));
            return Result::INVALID_PARAMETER;
        }
        
        
        recipients.emplace_back(CRecipient{GetScriptForDestination(new_coin_control.destChange), new_outputs_value, true});
        new_coin_control.destChange = CNoDestination();
    }
    if (coin_control.m_feerate) {
        
        
        
        CMutableTransaction temp_mtx{*wtx.tx};
        for (auto& txin : temp_mtx.vin) {
            txin.scriptSig.clear();
            txin.scriptWitness.SetNull();
        }
        temp_mtx.vout = txouts;
        const int64_t maxTxSize{CalculateMaximumSignedTxSize(CTransaction(temp_mtx), &wallet, &new_coin_control).vsize};
        Result res = CheckFeeRate(wallet, *new_coin_control.m_feerate, maxTxSize, old_fee, errors);
        if (res != Result::OK) {
            return res;
        }
    } else {