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 (!isScript && !(pubkey_dest == dest)) {
                    throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Consistency check failed");
                }
                
                if (isScript) {
                    CTxDestination destination;
                    if (ExtractDestination(script, destination)) {
                        if (!(destination == pubkey_dest)) {
                            throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Consistency check failed");
                        }
                    }
                }
                CKeyID vchAddress = pubKey.GetID();
                pwallet->MarkDirty();
                pwallet->SetAddressBook(vchAddress, label, "receive");
                if (pwallet->HaveKey(vchAddress)) {
                    throw JSONRPCError(RPC_WALLET_ERROR, "The wallet already contains the private key for this address or script");
                }
                pwallet->mapKeyMetadata[vchAddress].nCreateTime = timestamp;
                if (!pwallet->AddKeyPubKey(key, pubKey)) {
                    throw JSONRPCError(RPC_WALLET_ERROR, "Error adding key to wallet");
                }
                pwallet->UpdateTimeFirstKey(timestamp);
                success = true;
            }
            
            if (pubKeys.size() == 0 && keys.size() == 0) {
                if (::IsMine(*pwallet, script) == ISMINE_SPENDABLE) {
                    throw JSONRPCError(RPC_WALLET_ERROR, "The wallet already contains the private key for this address or script");