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 (nFD < MIN_CORE_FILEDESCRIPTORS)
        return InitError(_("Not enough file descriptors available."));
    nMaxConnections = std::min(nFD - MIN_CORE_FILEDESCRIPTORS - MAX_ADDNODE_CONNECTIONS, nMaxConnections);
    if (nMaxConnections < nUserMaxConnections)
        InitWarning(strprintf(_("Reducing -maxconnections from %d to %d, because of system limitations."), nUserMaxConnections, nMaxConnections));
    
    if (gArgs.IsArgSet("-debug")) {
        
        const std::vector<std::string> categories = gArgs.GetArgs("-debug");
        if (std::none_of(categories.begin(), categories.end(),
            [](std::string cat){return cat == "0" || cat == "none";})) {
            for (const auto& cat : categories) {
                if (!LogInstance().EnableCategory(cat)) {
                    InitWarning(strprintf(_("Unsupported logging category %s=%s."), "-debug", cat));
                }
            }
        }
    }
    
    for (const std::string& cat : gArgs.GetArgs("-debugexclude")) {
        if (!LogInstance().DisableCategory(cat)) {
            InitWarning(strprintf(_("Unsupported logging category %s=%s."), "-debugexclude", cat));
        }
    }
    
    int ratio = std::min<int>(std::max<int>(gArgs.GetArg("-checkmempool", chainparams.DefaultConsistencyChecks() ? 1 : 0), 0), 1000000);
    if (ratio != 0) {
        mempool.setSanityCheck(1.0 / ratio);
    }
    fCheckBlockIndex = gArgs.GetBoolArg("-checkblockindex", chainparams.DefaultConsistencyChecks());