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 
if (pindex == nullptr)
        return 0.0;
    int64_t nNow = time(nullptr);
    double fTxTotal;
    if (pindex->nChainTx <= data.nTxCount) {
        fTxTotal = data.nTxCount + (nNow - data.nTime) * data.dTxRate;
    } else {
        fTxTotal = pindex->nChainTx + (nNow - pindex->GetBlockTime()) * data.dTxRate;
    }
    return pindex->nChainTx / fTxTotal;
}
class CMainCleanup
{
public:
    CMainCleanup() {}
    ~CMainCleanup() {
        
        BlockMap::iterator it1 = mapBlockIndex.begin();
        for (; it1 != mapBlockIndex.end(); it1++)
            delete (*it1).second;
        mapBlockIndex.clear();
    }
} instance_of_cmaincleanup;