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 
{
    AssertLockNotHeld(cs_main);
    {
        CBlockIndex *pindex = nullptr;
        if (fNewBlock) *fNewBlock = false;
        CValidationState state;
        
        
        LOCK(cs_main);
        
        
        bool ret = CheckBlock(*pblock, state, chainparams.GetConsensus());
        if (ret) {
            
            ret = g_chainstate.AcceptBlock(pblock, state, chainparams, &pindex, fForceProcessing, nullptr, fNewBlock);
        }
        if (!ret) {
            GetMainSignals().BlockChecked(*pblock, state);
            return error("%s: AcceptBlock FAILED (%s)", __func__, FormatStateMessage(state));
        }
    }
    NotifyHeaderTip();
    CValidationState state; 
    if (!g_chainstate.ActivateBestChain(state, chainparams, pblock))
        return error("%s: ActivateBestChain failed (%s)", __func__, FormatStateMessage(state));
    return true;
}
bool TestBlockValidity(CValidationState& state, const CChainParams& chainparams, const CBlock& block, CBlockIndex* pindexPrev, bool fCheckPOW, bool fCheckMerkleRoot)