Greenlet failing on OSX and Windows

```
[2017-10-16 14:50:09,571] ERROR Site:... sands.git/packed-refs fileGet error: [Errno 2] No such file or directory: u'/Users/Manwe/Tools/ZeroNet/data/1RxTdD54fbEdVZs2hZCUBWirJf5bSsAUg/sands.git/packed-refs'
[2017-10-16 14:50:09,686] DEBUG Site:... Websocket send error: ConcurrentObjectUseError: This socket is already used by another greenlet: > in UiWebsocket.py line 197 > websocket.py line 349 > websocket.py line 333 > _socket2.pyo line 419 > _socket2.pyo line 355 > _socket2.pyo line 328 > _socket2.pyo line 176
[2017-10-16 14:50:09,686] DEBUG Site:... Websocket send error: ConcurrentObjectUseError: This socket is already used by another greenlet: > in UiWebsocket.py line 197 > websocket.py line 349 > websocket.py line 333 > _socket2.pyo line 419 > _socket2.pyo line 355 > _socket2.pyo line 328 > _socket2.pyo line 176
[2017-10-16 14:50:09,686] DEBUG Site:... Websocket send error: ConcurrentObjectUseError: This socket is already used by another greenlet: > in UiWebsocket.py line 197 > websocket.py line 349 > websocket.py line 333 > _socket2.pyo line 419 > _socket2.pyo line 355 > _socket2.pyo line 328 > _socket2.pyo line 176
```

...and a lot more messages. My site is trying to read many files at once, can it be related? This fails on OSX and works on Windows.