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 (CCryptoKeyStore::Unlock(_vMasterKey))
            {
                int64_t nStartTime = GetTimeMillis();
                crypter.SetKeyFromPassphrase(strNewWalletPassphrase, pMasterKey.second.vchSalt, pMasterKey.second.nDeriveIterations, pMasterKey.second.nDerivationMethod);
                pMasterKey.second.nDeriveIterations = static_cast<unsigned int>(pMasterKey.second.nDeriveIterations * (100 / ((double)(GetTimeMillis() - nStartTime))));
                nStartTime = GetTimeMillis();
                crypter.SetKeyFromPassphrase(strNewWalletPassphrase, pMasterKey.second.vchSalt, pMasterKey.second.nDeriveIterations, pMasterKey.second.nDerivationMethod);
                pMasterKey.second.nDeriveIterations = (pMasterKey.second.nDeriveIterations + static_cast<unsigned int>(pMasterKey.second.nDeriveIterations * 100 / ((double)(GetTimeMillis() - nStartTime)))) / 2;
                if (pMasterKey.second.nDeriveIterations < 25000)
                    pMasterKey.second.nDeriveIterations = 25000;
                LogPrintf("Wallet passphrase changed to an nDeriveIterations of %i\n", pMasterKey.second.nDeriveIterations);
                if (!crypter.SetKeyFromPassphrase(strNewWalletPassphrase, pMasterKey.second.vchSalt, pMasterKey.second.nDeriveIterations, pMasterKey.second.nDerivationMethod))
                    return false;
                if (!crypter.Encrypt(_vMasterKey, pMasterKey.second.vchCryptedKey))
                    return false;
                WalletBatch(*database).WriteMasterKey(pMasterKey.first, pMasterKey.second);
                if (fWasLocked)
                    Lock();
                return true;
            }
        }
    }
    return false;
}
void CWallet::ChainStateFlushed(const CBlockLocator& loc)
{
    WalletBatch batch(*database);
    batch.WriteBestBlock(loc);
}
void CWallet::SetMinVersion(enum WalletFeature nVersion, WalletBatch* batch_in, bool fExplicit)