In the log I see things like:

    2017-09-13 03:54:33 init message: Rescanning...
    2017-09-13 03:54:33 Rescanning last 68616 blocks (from block 416339)...
    2017-09-13 03:54:40 AddToWallet xxxxx  update
    2017-09-13 03:55:33 Still rescanning. At block 418849. Progress=0.549138

I would be interested to see the wallet file name on each of these log lines.

Would there be any interest in merging such a PR?
return nullptr;
        }
        else if (nLoadWalletRet == DBErrors::NONCRITICAL_ERROR)
        {
            InitWarning(strprintf(_("Error reading %s! All keys read correctly, but transaction data"
                                         " or address book entries might be missing or incorrect."),
                walletFile));
        }
        else if (nLoadWalletRet == DBErrors::TOO_NEW) {
            InitError(strprintf(_("Error loading %s: Wallet requires newer version of %s"), walletFile, _(PACKAGE_NAME)));
            return nullptr;
        }
        else if (nLoadWalletRet == DBErrors::NEED_REWRITE)
        {
            InitError(strprintf(_("Wallet needed to be rewritten: restart %s to complete"), _(PACKAGE_NAME)));
            return nullptr;
        }
        else {
            InitError(strprintf(_("Error loading %s"), walletFile));
            return nullptr;
        }
    }
    int prev_version = walletInstance->nWalletVersion;
    if (gArgs.GetBoolArg("-upgradewallet", fFirstRun))
    {
        int nMaxVersion = gArgs.GetArg("-upgradewallet", 0);
        if (nMaxVersion == 0) 
        {
            LogPrintf("Performing wallet upgrade to %i\n", FEATURE_LATEST);
            nMaxVersion = FEATURE_LATEST;