While regtesting with [bitcoin-spock](https://github.com/msgilligan/bitcoin-spock) I noticed at some point the transaction creation via `sendtoaddress -> CreateTransaction()` fails, because the created transaction is larger than `MAX_STANDARD_TX_SIZE`.

During the process a lot of raw transactions are created, which have smallish outputs and when then using `sendtoaddress`, it appears to attempt to create a transaction that spends too many of those dust-ish outputs.

The transaction to create does not have many outputs, but it looks like it's caused by the coin selection, which selects too many inputs. Testing was done with a 0.9 branch, but on the first glimpse I believe this issue is as well be present in 0.10. If this is a known issue, and if there is already a guard against this behavior, I'd be happy about a hint.

Sorry in advance, I do not have a test script to reproduce this issue in an isolated manner. A potential fix would probably require to adjust the coin selection, so that it selects a combination of coins, which, in addition to the size of the rest of the transaction, is still smaller than the limit.

#ifndef BITCOIN_WALLET_COINSELECTION_H
#define BITCOIN_WALLET_COINSELECTION_H
#include <consensus/amount.h>
#include <policy/feerate.h>
#include <primitives/transaction.h>
#include <random.h>
#include <optional>
namespace wallet {
static constexpr CAmount CHANGE_LOWER{50000};
static constexpr CAmount CHANGE_UPPER{1000000};
struct COutput {
private:
    
    std::optional<CAmount> effective_value;
    
    std::optional<CAmount> fee;