Fix issues with FileStorageExperiment not closing open files

[rajatvd]

No description provided.

[JarnoRFB]

@rajatvd thanks for your contribution! Can you elaborate on why info.json might not be present?

[rajatvd]

By default if we use just a FileStorageObserver, the info.json file is not created.

For example, test.py :

from sacred import Experiment
from sacred.observers import FileStorageObserver

ex = Experiment()
ex.observers.append(FileStorageObserver.create("my_runs"))


@ex.automain
def my_main(_run):
    print("Hello world!")
    _run.log_scalar("foo", 42)

Running
python test.py

leads to directory structure that looks like

- my_runs
  - 1
     - config.json
     - cout.txt
     - metrics.json
     - run.json