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 
{
    setEntries parentHashes;
    const CTransaction &tx = entry.GetTx();
    if (fSearchForParents) {
        
        
        
        for (unsigned int i = 0; i < tx.vin.size(); i++) {
            boost::optional<txiter> piter = GetIter(tx.vin[i].prevout.hash);
            if (piter) {
                parentHashes.insert(*piter);
                if (parentHashes.size() + 1 > limitAncestorCount) {
                    errString = strprintf("too many unconfirmed parents [limit: %u]", limitAncestorCount);
                    return false;
                }
            }
        }
    } else {
        
        
        txiter it = mapTx.iterator_to(entry);
        parentHashes = GetMemPoolParents(it);
    }
    size_t totalSizeWithAncestors = entry.GetTxSize();