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.

{
    addrman.SetServices(addr, nServices);
}
void CConnman::MarkAddressGood(const CAddress& addr)
{
    addrman.Good(addr);
}
void CConnman::AddNewAddress(const CAddress& addr, const CAddress& addrFrom, int64_t nTimePenalty)
{
    addrman.Add(addr, addrFrom, nTimePenalty);
}
void CConnman::AddNewAddresses(const std::vector<CAddress>& vAddr, const CAddress& addrFrom, int64_t nTimePenalty)
{
    addrman.Add(vAddr, addrFrom, nTimePenalty);
}
std::vector<CAddress> CConnman::GetAddresses()
{
    return addrman.GetAddr();
}
bool CConnman::AddNode(const std::string& strNode)
{
    LOCK(cs_vAddedNodes);
    for(std::vector<std::string>::const_iterator it = vAddedNodes.begin(); it != vAddedNodes.end(); ++it) {
        if (strNode == *it)
            return false;
    }
    vAddedNodes.push_back(strNode);
    return true;
}
bool CConnman::RemoveAddedNode(const std::string& strNode)