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.

break;
            else if (ret != 0)
            {
                LogPrintf("Error reading next record from wallet database\n");
                return DB_CORRUPT;
            }
            
            string strType, strErr;
            if (!ReadKeyValue(pwallet, ssKey, ssValue, wss, strType, strErr))
            {
                
                
                if (IsKeyType(strType))
                    result = DB_CORRUPT;
                else
                {
                    
                    fNoncriticalErrors = true; 
                    if (strType == "tx")
                        
                        SoftSetBoolArg("-rescan", true);
                }
            }
            if (!strErr.empty())
                LogPrintf("%s\n", strErr);
        }
        pcursor->close();
    }
    catch (const boost::thread_interrupted&) {
        throw;