Current bitcoin-master on testnet, `maxconnections=8` in the config file. Running in VM that doesn't have public IP and is not reachable from the Internet.

Wait until you have 8 peers.

```
telnet localhost 18333
```

It will result in:

```
Assertion failed: (nMaxInbound > 0), function AcceptConnection, file net.cpp, line 973.
```

First found in https://github.com/bitcoin/bitcoin/pull/8996, but can be reproduced on master.

bool fFeeler = false;
        if (nOutbound >= nMaxOutbound) {
            int64_t nTime = GetTimeMicros(); 
            if (nTime > nNextFeeler) {
                nNextFeeler = PoissonNextSend(nTime, FEELER_INTERVAL);
                fFeeler = true;
            } else {
                continue;
            }
        }
        int64_t nANow = GetAdjustedTime();
        int nTries = 0;
        while (true)
        {
            CAddrInfo addr = addrman.Select(fFeeler);
            
            if (!addr.IsValid() || setConnected.count(addr.GetGroup()) || IsLocal(addr))
                break;
            
            
            
            nTries++;
            if (nTries > 100)