Reported here: https://github.com/bitcoin/bitcoin/pull/10244#issuecomment-378035305

Travis log here: https://travis-ci.org/bitcoin/bitcoin/jobs/361243719#L2810

Note the JSON exception:

```
test_framework.authproxy.JSONRPCException: The mempool was not loaded yet (-1) 
```

That exception was introduced here: https://github.com/bitcoin/bitcoin/commit/cb1e319fe9e198c9c5cf5236fe9af5a3d748b9e8#diff-a0c8f511d90e83aa9b5857e819ced344R1617

cc @jtimon 
void operator() (CTxMemPoolEntry &e) { e.UpdateFeeDelta(feeDelta); }
private:
    int64_t feeDelta;
};
struct update_lock_points
{
    explicit update_lock_points(const LockPoints& _lp) : lp(_lp) { }
    void operator() (CTxMemPoolEntry &e) { e.UpdateLockPoints(lp); }
private:
    const LockPoints& lp;
};
struct mempoolentry_txid
{
    typedef uint256 result_type;
    result_type operator() (const CTxMemPoolEntry &entry) const
    {
        return entry.GetTx().GetHash();
    }
    result_type operator() (const CTransactionRef& tx) const
    {
        return tx->GetHash();
    }
};
/** \class CompareTxMemPoolEntryByDescendantScore
 *
 *  Sort an entry by max(score/size of entry's tx, score/size with all descendants).
 */
class CompareTxMemPoolEntryByDescendantScore