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 
return g_chainstate.ResetBlockFailureFlags(pindex);
}
CBlockIndex* CChainState::AddToBlockIndex(const CBlockHeader& block)
{
    AssertLockHeld(cs_main);
    
    uint256 hash = block.GetHash();
    BlockMap::iterator it = mapBlockIndex.find(hash);
    if (it != mapBlockIndex.end())
        return it->second;
    
    CBlockIndex* pindexNew = new CBlockIndex(block);
    
    
    
    pindexNew->nSequenceId = 0;
    BlockMap::iterator mi = mapBlockIndex.insert(std::make_pair(hash, pindexNew)).first;