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 
{
    lockPoints = lp;
}
size_t CTxMemPoolEntry::GetTxSize() const
{
    return GetVirtualTransactionSize(nTxWeight, sigOpCost);
}
void CTxMemPool::UpdateForDescendants(txiter updateIt, cacheMap &cachedDescendants, const std::set<uint256> &setExclude)
{
    setEntries stageEntries, setAllDescendants;
    stageEntries = GetMemPoolChildren(updateIt);
    while (!stageEntries.empty()) {
        const txiter cit = *stageEntries.begin();
        setAllDescendants.insert(cit);
        stageEntries.erase(cit);
        const setEntries &setChildren = GetMemPoolChildren(cit);
        for (txiter childEntry : setChildren) {
            cacheMap::iterator cacheIt = cachedDescendants.find(childEntry);
            if (cacheIt != cachedDescendants.end()) {
                
                
                for (txiter cacheEntry : cacheIt->second) {
                    setAllDescendants.insert(cacheEntry);
                }
            } else if (!setAllDescendants.count(childEntry)) {
                
                stageEntries.insert(childEntry);
            }