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?
if (filter == ISMINE_SPENDABLE) {
        cache = &nAvailableCreditCached;
        cache_used = &fAvailableCreditCached;
    } else if (filter == ISMINE_WATCH_ONLY) {
        cache = &nAvailableWatchCreditCached;
        cache_used = &fAvailableWatchCreditCached;
    }
    if (fUseCache && cache_used && *cache_used) {
        return *cache;
    }
    CAmount nCredit = 0;
    uint256 hashTx = GetHash();
    for (unsigned int i = 0; i < tx->vout.size(); i++)
    {
        if (!pwallet->IsSpent(hashTx, i))
        {
            const CTxOut &txout = tx->vout[i];
            nCredit += pwallet->GetCredit(txout, filter);
            if (!MoneyRange(nCredit))
                throw std::runtime_error(std::string(__func__) + " : value out of range");
        }
    }
    if (cache) {
        *cache = nCredit;
        assert(cache_used);
        *cache_used = true;
    }
    return nCredit;
}
CAmount CWalletTx::GetImmatureWatchOnlyCredit(const bool fUseCache) const