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 (initialSync || !pBlockIndex)
        return;
    std::string strCmd = gArgs.GetArg("-blocknotify", "");
    if (!strCmd.empty()) {
        boost::replace_all(strCmd, "%s", pBlockIndex->GetBlockHash().GetHex());
        std::thread t(runCommand, strCmd);
        t.detach(); 
    }
}
static bool fHaveGenesis = false;
static Mutex g_genesis_wait_mutex;
static std::condition_variable g_genesis_wait_cv;
static void BlockNotifyGenesisWait(bool, const CBlockIndex *pBlockIndex)