`ScanForWalletTransactions()` has the following comment about its return value:

```
 * Returns null if scan was successful. Otherwise, if a complete rescan was not
 * possible (due to pruning or corruption), returns pointer to the most recent
 * block that could not be scanned.
```

This is not strictly true. If `abortrescan` is called, then `ScanForWalletTransactions()` will return `nullptr`, even though the scan wasn't successful to the tip.

This in turn causes a minor bug in `importmulti`, where the call doesn't return the correct error and warning about potentially not finding transactions if `abortrescan` was called.

I think the correct fix is for `ScanForWalletTransactions()` to inform the caller that the rescan was aborted.
{
    CKeyMetadata meta;
    {
        LOCK(cs_wallet);
        auto it = mapKeyMetadata.find(keyID);
        if (it != mapKeyMetadata.end()) {
            meta = it->second;
        }
    }
    if (!meta.hdKeypath.empty()) {
        if (!ParseHDKeypath(meta.hdKeypath, info.path)) return false;
        
        CKey key;
        GetKey(meta.hd_seed_id, key);
        CExtKey masterKey;
        masterKey.SetSeed(key.begin(), key.size());
        
        CKeyID masterid = masterKey.key.GetPubKey().GetID();
        std::copy(masterid.begin(), masterid.begin() + 4, info.fingerprint);
    } else { 
        std::copy(keyID.begin(), keyID.begin() + 4, info.fingerprint);
    }
    return true;
}