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 
{
    mapLinks.clear();
    mapTx.clear();
    mapNextTx.clear();
    totalTxSize = 0;
    cachedInnerUsage = 0;
    lastRollingFeeUpdate = GetTime();
    blockSinceLastRollingFeeBump = false;
    rollingMinimumFeeRate = 0;
    ++nTransactionsUpdated;
}
void CTxMemPool::clear()
{
    LOCK(cs);
    _clear();
}
static void CheckInputsAndUpdateCoins(const CTransaction& tx, CCoinsViewCache& mempoolDuplicate, const int64_t spendheight)
{
    CValidationState state;
    CAmount txfee = 0;
    bool fCheckResult = tx.IsCoinBase() || Consensus::CheckTxInputs(tx, state, mempoolDuplicate, spendheight, txfee);
    assert(fCheckResult);
    UpdateCoins(tx, mempoolDuplicate, 1000000);
}
void CTxMemPool::check(const CCoinsViewCache *pcoins) const