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 
std::set<std::string> setDepends;
    for (const CTxIn& txin : tx.vin)
    {
        if (pool.exists(txin.prevout.hash))
            setDepends.insert(txin.prevout.hash.ToString());
    }
    UniValue depends(UniValue::VARR);
    for (const std::string& dep : setDepends)
    {
        depends.push_back(dep);
    }
    info.pushKV("depends", depends);
    UniValue spent(UniValue::VARR);
    const CTxMemPool::txiter& it = pool.mapTx.find(tx.GetHash());
    const CTxMemPool::setEntries& setChildren = pool.GetMemPoolChildren(it);
    for (CTxMemPool::txiter childiter : setChildren) {
        spent.push_back(childiter->GetTx().GetHash().ToString());
    }
    info.pushKV("spentby", spent);
    
    bool rbfStatus = false;
    RBFTransactionState rbfState = IsRBFOptIn(tx, pool);
    if (rbfState == RBFTransactionState::UNKNOWN) {
        throw JSONRPCError(RPC_MISC_ERROR, "Transaction is not in mempool");
    } else if (rbfState == RBFTransactionState::REPLACEABLE_BIP125) {
        rbfStatus = true;
    }
    info.pushKV("bip125-replaceable", rbfStatus);
}
UniValue MempoolToJSON(const CTxMemPool& pool, bool verbose)