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?
CScript script;
        CTxDestination dest;
        if (!isScript) {
            dest = DecodeDestination(output);
            if (!IsValidDestination(dest)) {
                throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid address");
            }
            script = GetScriptForDestination(dest);
        } else {
            if (!IsHex(output)) {
                throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid scriptPubKey");
            }
            std::vector<unsigned char> vData(ParseHex(output));
            script = CScript(vData.begin(), vData.end());
        }
        
        if (watchOnly && keys.size()) {
            throw JSONRPCError(RPC_INVALID_PARAMETER, "Incompatibility found between watchonly and keys");
        }
        
        if (internal && data.exists("label")) {
            throw JSONRPCError(RPC_INVALID_PARAMETER, "Incompatibility found between internal and label");
        }
        
        if (!internal && isScript) {
            throw JSONRPCError(RPC_INVALID_PARAMETER, "Internal must be set for hex scriptPubKey");
        }
        
        if (!isP2SH && (keys.size() > 1 || pubKeys.size() > 1)) {