`bitcoin.conf`:
```
...
testnet=1
# [wallets]
test.wallet=test_alpha
test.wallet=alpha_wallet
test.wallet=none
...
```

Run bitcoin client.

`debug.log`:
```
...
2019-02-03T13:09:23Z Using wallet directory /home/hebasto/.bitcoin/testnet3/wallets
2019-02-03T13:09:23Z init message: Verifying wallet(s)...
2019-02-03T13:09:23Z Using BerkeleyDB version Berkeley DB 4.8.30: (April  9, 2010)
2019-02-03T13:09:23Z Using wallet wallet.dat
2019-02-03T13:09:23Z BerkeleyEnvironment::Open: LogDir=/home/hebasto/.bitcoin/testnet3/wallets/test_alpha/database ErrorFile=/home/hebasto/.bitcoin/testnet3/wallets/test_alpha/db.log
2019-02-03T13:09:23Z Using BerkeleyDB version Berkeley DB 4.8.30: (April  9, 2010)
2019-02-03T13:09:23Z Using wallet wallet.dat
2019-02-03T13:09:23Z BerkeleyEnvironment::Open: LogDir=/home/hebasto/.bitcoin/testnet3/wallets/alpha_wallet/database ErrorFile=/home/hebasto/.bitcoin/testnet3/wallets/alpha_wallet/db.log
2019-02-03T13:09:23Z Using BerkeleyDB version Berkeley DB 4.8.30: (April  9, 2010)
2019-02-03T13:09:23Z Using wallet wallet.dat
2019-02-03T13:09:23Z BerkeleyEnvironment::Open: LogDir=/home/hebasto/.bitcoin/testnet3/wallets/none/database ErrorFile=/home/hebasto/.bitcoin/testnet3/wallets/none/db.log9
...
```

In multi-wallet environment a wallet database file reference (`wallet.dat`) without a wallet name (e.g., `test_alpha`) could be confusing.
{
            boost::this_thread::interruption_point();
            std::map<std::string, int>::iterator mi = env->mapFileUseCount.find(strFile);
            if (mi != env->mapFileUseCount.end())
            {
                LogPrint(BCLog::DB, "Flushing %s\n", strFile);
                int64_t nStart = GetTimeMillis();
                
                env->CloseDb(strFile);
                env->CheckpointLSN(strFile);
                env->mapFileUseCount.erase(mi++);
                LogPrint(BCLog::DB, "Flushed %s %dms\n", strFile, GetTimeMillis() - nStart);
                ret = true;
            }
        }
    }
    return ret;
}
bool BerkeleyDatabase::Rewrite(const char* pszSkip)
{
    return BerkeleyBatch::Rewrite(*this, pszSkip);
}
bool BerkeleyDatabase::Backup(const std::string& strDest)
{
    if (IsDummy()) {
        return false;
    }
    while (true)
    {
        {