crash on startup (std::system_error) on pine64
Managed to get openmonero running on my pine64 yesterday. Today it's crashing on startup. Daemon (testnet) is running, fully synced. Any clues? 

```
$ ./openmonero -t
Blockchain path: /media/external/testnet/lmdb
2017-07-22 08:00:40.365	      7f991c4000	INFO 	global	contrib/epee/src/mlog.cpp:145	New log categories: *:WARNING,net:FATAL,net.p2p:FATAL,net.cn:FATAL,global:INFO,verify:FATAL,stacktrace:INFO
Check block height: 959259 no of mempool txs: 0
Start the service at http://localhost:1984
terminate called after throwing an instance of 'std::system_error'
terminate called recursively
Aborted
```

Full BT https://paste.fedoraproject.org/paste/fxZOx9rg3TuRJVqHiYpHJQ/raw
