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?
{
public:
    CPubKey vchPubKey;
    CAccount()
    {
        SetNull();
    }
    void SetNull()
    {
        vchPubKey = CPubKey();
    }
    ADD_SERIALIZE_METHODS;
    template <typename Stream, typename Operation>
    inline void SerializationOp(Stream& s, Operation ser_action) {
        int nVersion = s.GetVersion();
        if (!(s.GetType() & SER_GETHASH))
            READWRITE(nVersion);
        READWRITE(vchPubKey);
    }
};
class WalletRescanReserver
{
private:
    CWallet* m_wallet;
    bool m_could_reserve;
public:
    explicit WalletRescanReserver(CWallet* w) : m_wallet(w), m_could_reserve(false) {}