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 
}
        {
            LOCK(cs_main);
            CBlockIndex* starting_tip = chainActive.Tip();
            bool blocks_connected = false;
            do {
                
                
                ConnectTrace connectTrace(mempool); 
                if (pindexMostWork == nullptr) {
                    pindexMostWork = FindMostWorkChain();
                }
                
                if (pindexMostWork == nullptr || pindexMostWork == chainActive.Tip()) {
                    break;
                }
                bool fInvalidFound = false;
                std::shared_ptr<const CBlock> nullBlockPtr;
                if (!ActivateBestChainStep(state, chainparams, pindexMostWork, pblock && pblock->GetHash() == pindexMostWork->GetBlockHash() ? pblock : nullBlockPtr, fInvalidFound, connectTrace))
                    return false;
                blocks_connected = true;
                if (fInvalidFound) {
                    
                    pindexMostWork = nullptr;
                }
                pindexNewTip = chainActive.Tip();
                for (const PerBlockConnectTrace& trace : connectTrace.GetBlocksConnected()) {
                    assert(trace.pblock && trace.pindex);
                    GetMainSignals().BlockConnected(trace.pblock, trace.pindex, trace.conflictedTxs);
                }