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.

{
    std::vector<NodeEvictionCandidate> vEvictionCandidates;
    {
        LOCK(cs_vNodes);
        BOOST_FOREACH(CNode *node, vNodes) {
            if (node->fWhitelisted)
                continue;
            if (!node->fInbound)
                continue;
            if (node->fDisconnect)
                continue;
            NodeEvictionCandidate candidate = {node->id, node->nTimeConnected, node->nMinPingUsecTime,
                                               node->nLastBlockTime, node->nLastTXTime, node->fNetworkNode,
                                               node->fRelayTxes, node->pfilter != NULL, node->addr, node->nKeyedNetGroup};
            vEvictionCandidates.push_back(candidate);
        }
    }
    if (vEvictionCandidates.empty()) return false;