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 (IsCoinBase() && GetBlocksToMaturity() > 0 && IsInMainChain())
    {
        if (fUseCache && fImmatureWatchCreditCached)
            return nImmatureWatchCreditCached;
        nImmatureWatchCreditCached = pwallet->GetCredit(*tx, ISMINE_WATCH_ONLY);
        fImmatureWatchCreditCached = true;
        return nImmatureWatchCreditCached;
    }
    return 0;
}
CAmount CWalletTx::GetChange() const
{
    if (fChangeCached)
        return nChangeCached;
    nChangeCached = pwallet->GetChange(*tx);
    fChangeCached = true;
    return nChangeCached;
}
bool CWalletTx::InMempool() const
{
    return fInMempool;
}
bool CWalletTx::IsTrusted() const