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);
    return mapNextTx.count(outpoint);
}
unsigned int CTxMemPool::GetTransactionsUpdated() const
{
    LOCK(cs);
    return nTransactionsUpdated;
}
void CTxMemPool::AddTransactionsUpdated(unsigned int n)
{
    LOCK(cs);
    nTransactionsUpdated += n;
}
void CTxMemPool::addUnchecked(const CTxMemPoolEntry &entry, setEntries &setAncestors, bool validFeeEstimate)
{
    NotifyEntryAdded(entry.GetSharedTx());
    
    
    
    indexed_transaction_set::iterator newit = mapTx.insert(entry).first;
    mapLinks.insert(make_pair(newit, TxLinks()));
    
    
    
    CAmount delta{0};
    ApplyDelta(entry.GetTx().GetHash(), delta);
    if (delta) {
            mapTx.modify(newit, update_fee_delta(delta));