Progress bar + file observer = tee timeout error

[thisiscam]

Hi,

I was able to consistently reproduce a tee timeout on sacred 0.8.4 and using tqdm progress bar:

# test_sacred_tqdm.py
import sacred
import tqdm

ex = sacred.Experiment()

@ex.automain
def main():
  for i in tqdm.tqdm(range(100)):
    pass

Running with command

python test_sacred_tqdm.py -F tmp1/

results in

/python3.9/site-packages/sacred/stdout_capturing.py:179: UserWarning: tee_stdout.wait timeout. Forcibly terminating.
  warnings.warn("tee_stdout.wait timeout. Forcibly terminating.")
/python3.9/site-packages/sacred/stdout_capturing.py:185: UserWarning: tee_stderr.wait timeout. Forcibly terminating.
  warnings.warn("tee_stderr.wait timeout. Forcibly terminating.")

Seems related to #289 and #440