Weird issue with `peewee`

I seem to have encountered a weird issue with `peewee` when running https://github.com/vwxyzjn/gym-microrts/blob/oai5/experiments/ppo_gridnet_oai5.py:

```
ne 3160, in execute_sql
cursor.execute(sql, params or ())
peewee.OperationalError: database is locked
exception calling callback for
Traceback (most recent call last):
File "/environment/miniconda3/lib/python3.7/concurrent/futures/_base.py", line 324, in _invoke_callbacks
callback(self)
File "ppo_gridnet_oai5.py", line 275, in on_evaluation_done
model_path, output_path = future.result()
File "/environment/miniconda3/lib/python3.7/concurrent/futures/_base.py", line 428, in result
return self.__get_result()
File "/environment/miniconda3/lib/python3.7/concurrent/futures/_base.py", line 384, in __get_result
raise self._exception
File "/environment/miniconda3/lib/python3.7/concurrent/futures/thread.py", line 57, in run
result = self.fn(*self.args, **self.kwargs)
File "ppo_gridnet_oai5.py", line 257, in run_evaluation
assert return_code == 0
AssertionError
SPS: 980
```

ran in a computer that didn't quite get the full trace...