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?
/**
     * keystore implementation
     * Generate a new key
     */
    CPubKey GenerateNewKey(WalletBatch& batch, bool internal = false) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
    
    bool AddKeyPubKey(const CKey& key, const CPubKey &pubkey) override EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
    bool AddKeyPubKeyWithDB(WalletBatch &batch,const CKey& key, const CPubKey &pubkey) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
    
    bool LoadKey(const CKey& key, const CPubKey &pubkey) { return CCryptoKeyStore::AddKeyPubKey(key, pubkey); }
    
    void LoadKeyMetadata(const CKeyID& keyID, const CKeyMetadata &metadata) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
    void LoadScriptMetadata(const CScriptID& script_id, const CKeyMetadata &metadata) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
    bool LoadMinVersion(int nVersion) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet) { AssertLockHeld(cs_wallet); nWalletVersion = nVersion; nWalletMaxVersion = std::max(nWalletMaxVersion, nVersion); return true; }
    void UpdateTimeFirstKey(int64_t nCreateTime) EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);
    
    bool AddCryptedKey(const CPubKey &vchPubKey, const std::vector<unsigned char> &vchCryptedSecret) override;
    
    bool LoadCryptedKey(const CPubKey &vchPubKey, const std::vector<unsigned char> &vchCryptedSecret);
    bool AddCScript(const CScript& redeemScript) override;
    bool LoadCScript(const CScript& redeemScript);
    
    bool AddDestData(const CTxDestination &dest, const std::string &key, const std::string &value);
    
    bool EraseDestData(const CTxDestination &dest, const std::string &key);
    
    void LoadDestData(const CTxDestination &dest, const std::string &key, const std::string &value);
    
    bool GetDestData(const CTxDestination &dest, const std::string &key, std::string *value) const;