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 
bool fMempool = true;
    if (!request.params[2].isNull())
        fMempool = request.params[2].get_bool();
    Coin coin;
    if (fMempool) {
        LOCK(mempool.cs);
        CCoinsViewMemPool view(pcoinsTip.get(), mempool);
        if (!view.GetCoin(out, coin) || mempool.isSpent(out)) {
            return NullUniValue;
        }
    } else {
        if (!pcoinsTip->GetCoin(out, coin)) {
            return NullUniValue;
        }
    }
    const CBlockIndex* pindex = LookupBlockIndex(pcoinsTip->GetBestBlock());
    ret.pushKV("bestblock", pindex->GetBlockHash().GetHex());
    if (coin.nHeight == MEMPOOL_HEIGHT) {
        ret.pushKV("confirmations", 0);
    } else {
        ret.pushKV("confirmations", (int64_t)(pindex->nHeight - coin.nHeight + 1));
    }
    ret.pushKV("value", ValueFromAmount(coin.out.nValue));
    UniValue o(UniValue::VOBJ);
    ScriptPubKeyToUniv(coin.out.scriptPubKey, o, true);
    ret.pushKV("scriptPubKey", o);
    ret.pushKV("coinbase", (bool)coin.fCoinBase);
    return ret;
}
static UniValue verifychain(const JSONRPCRequest& request)