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?
* the watch key did not previously have a timestamp associated with it.
     * Because this is an inherited virtual method, it is accessible despite
     * being marked private, but it is marked private anyway to encourage use
     * of the other AddWatchOnly which accepts a timestamp and sets
     * nTimeFirstKey more intelligently for more efficient rescans.
     */
    bool AddWatchOnly(const CScript& dest) override EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
    /**
     * Wallet filename from wallet=<path> command line or config option.
     * Used in debug logs and to send RPCs to the right wallet instance when
     * more than one wallet is loaded.
     */
    std::string m_name;
    
    std::unique_ptr<WalletDatabase> database;
    /**
     * The following is used to keep track of how far behind the wallet is
     * from the chain sync, and to allow clients to block on us being caught up.
     *
     * Note that this is *not* how far we've processed, we may need some rescan
     * to have seen all transactions in the chain, but is only used to track
     * live BlockConnected callbacks.
     *
     * Protected by cs_main (see BlockUntilSyncedToCurrentChain)
     */
    const CBlockIndex* m_last_block_processed = nullptr;
public:
    /*
     * Main wallet lock.
     * This lock protects all the fields added by CWallet.