On my Linux Mint 19.1:
```bash
$ umask
0022
```

After the first run of `bitcoin-qt -sysperm=false` the `0700` permissions are expected for both the datadir (`~/.bitcoin`) and the walletdir (`~/.bitcoin/wallets`).

Actually, the directories are created with such access permissions:
```bash
$ stat ~/.bitcoin | grep Uid
Access: (0755/drwxr-xr-x)  Uid: ( 1000/ hebasto)   Gid: ( 1000/ hebasto)
$ stat ~/.bitcoin/wallets | grep Uid
Access: (0755/drwxr-xr-x)  Uid: ( 1000/ hebasto)   Gid: ( 1000/ hebasto)
```

Refs:
- #4286
- #13371
- #13389

NOTE: reading through the initial PR #4286 makes me think it was controversial. Is it a better and simpler way to just get rid of `-sysperm` option? I believe a user who needs this option can easily run `chown` command.
{
    try {
        while (!*m_interrupt) {
            Sock::Event occurred;
            if (!conn.sock->Wait(MAX_WAIT_FOR_IO, Sock::RECV, &occurred)) {
                throw std::runtime_error("wait on socket failed");
            }
            if (occurred == 0) {
                
                continue;
            }
            const std::string& peer_dest =
                conn.sock->RecvUntilTerminator('\n', MAX_WAIT_FOR_IO, *m_interrupt, MAX_MSG_SIZE);
            conn.peer = CService(DestB64ToAddr(peer_dest), I2P_SAM31_PORT);
            return true;
        }
    } catch (const std::runtime_error& e) {
        Log("Error accepting: %s", e.what());
        CheckControlSock();
    }
    return false;
}
bool Session::Connect(const CService& to, Connection& conn, bool& proxy_error)