When importing a watch-only address over `importmulti` with a specific timestamp, the wallet's `nTimeFirstKey` will be set to 1.
I think we should add a optional timestamp to `CWallet::AddWatchOnly()` and use it when importing addresses or pubkeys.

{
                if (mapWallet.count(txin.prevout.hash))
                    mapWallet[txin.prevout.hash].MarkDirty();
            }
        }
    }
    return true;
}
void CWallet::MarkConflicted(const uint256& hashBlock, const uint256& hashTx)
{
    LOCK2(cs_main, cs_wallet);
    int conflictconfirms = 0;
    if (mapBlockIndex.count(hashBlock)) {
        CBlockIndex* pindex = mapBlockIndex[hashBlock];
        if (chainActive.Contains(pindex)) {
            conflictconfirms = -(chainActive.Height() - pindex->nHeight + 1);
        }
    }
    
    
    
    
    if (conflictconfirms >= 0)
        return;