Comment 3 for bug 1806089

Hmm, my proposed solution may be wrong, I did a small experiment. I created the following script:
```
$ cat script.py

import json
import sys

with open(sys.argv[1]) as json_file:
    json_data = json.load(json_file)
    print(json_data)
```

The script should mock the tempest cleanup call which currently fails. When I execute the script by using python3.6, it works, but running tempest cleanup by the same python3.6 leads to the traceback .. that's very strange. Also I noticed that a different codecs file is used.
It could mean that something is overridden/hardcoded in tempest .. I need to investigate that more.