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.
if (node.connman) node.connman->Stop();
    StopTorControl();
    
    
    if (node.scheduler) node.scheduler->stop();
    if (node.chainman && node.chainman->m_load_block.joinable()) node.chainman->m_load_block.join();
    StopScriptCheckWorkerThreads();
    
    
    node.peerman.reset();
    node.connman.reset();
    node.banman.reset();
    node.addrman.reset();
    node.netgroupman.reset();
    if (node.mempool && node.mempool->GetLoadTried() && ShouldPersistMempool(*node.args)) {
        DumpMempool(*node.mempool, MempoolPath(*node.args));
    }
    
    if (node.fee_estimator) node.fee_estimator->Flush();
    
    if (node.chainman) {
        LOCK(cs_main);
        for (Chainstate* chainstate : node.chainman->GetAll()) {
            if (chainstate->CanFlushToDisk()) {
                chainstate->ForceFlushStateToDisk();
            }
        }
    }