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 
assert(!blocksConnected.back().pindex);
        assert(blocksConnected.back().conflictedTxs->empty());
        blocksConnected.pop_back();
        return blocksConnected;
    }
    void NotifyEntryRemoved(CTransactionRef txRemoved, MemPoolRemovalReason reason) {
        assert(!blocksConnected.back().pindex);
        if (reason == MemPoolRemovalReason::CONFLICT) {
            blocksConnected.back().conflictedTxs->emplace_back(std::move(txRemoved));
        }
    }
};
/**
 * Connect a new block to chainActive. pblock is either nullptr or a pointer to a CBlock
 * corresponding to pindexNew, to bypass loading it again from disk.
 *
 * The block is added to connectTrace if connection succeeds.
 */
bool CChainState::ConnectTip(CValidationState& state, const CChainParams& chainparams, CBlockIndex* pindexNew, const std::shared_ptr<const CBlock>& pblock, ConnectTrace& connectTrace, DisconnectedBlockTransactions &disconnectpool)