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 
stats.insert(stat);
        }
    }
    const CBlock block = GetBlockChecked(pindex);
    const bool do_all = stats.size() == 0; 
    const bool do_mediantxsize = do_all || stats.count("mediantxsize") != 0;
    const bool do_medianfee = do_all || stats.count("medianfee") != 0;
    const bool do_feerate_percentiles = do_all || stats.count("feerate_percentiles") != 0;
    const bool loop_inputs = do_all || do_medianfee || do_feerate_percentiles ||
        SetHasKeys(stats, "utxo_size_inc", "totalfee", "avgfee", "avgfeerate", "minfee", "maxfee", "minfeerate", "maxfeerate");
    const bool loop_outputs = do_all || loop_inputs || stats.count("total_out");
    const bool do_calculate_size = do_mediantxsize ||
        SetHasKeys(stats, "total_size", "avgtxsize", "mintxsize", "maxtxsize", "swtotal_size");
    const bool do_calculate_weight = do_all || SetHasKeys(stats, "total_weight", "avgfeerate", "swtotal_weight", "avgfeerate", "feerate_percentiles", "minfeerate", "maxfeerate");
    const bool do_calculate_sw = do_all || SetHasKeys(stats, "swtxs", "swtotal_size", "swtotal_weight");
    if (loop_inputs && !g_txindex) {
        throw JSONRPCError(RPC_INVALID_PARAMETER, "One or more of the selected stats requires -txindex enabled");
    }
    CAmount maxfee = 0;
    CAmount maxfeerate = 0;
    CAmount minfee = MAX_MONEY;
    CAmount minfeerate = MAX_MONEY;
    CAmount total_out = 0;
    CAmount totalfee = 0;
    int64_t inputs = 0;
    int64_t maxtxsize = 0;
    int64_t mintxsize = MAX_BLOCK_SERIALIZED_SIZE;
    int64_t outputs = 0;
    int64_t swtotal_size = 0;
    int64_t swtotal_weight = 0;