added test_user_script_crash test (#709)

[nurbal]

Description

Detects if a by-design crashing black-box script Traceback is visible in the stderr output of orion.

The test succeeds, which indicates that the stacktrace is indeed visible by the user on his terminal output.

Is meant to implement issue #709

Changes

Just a test, since the behaviour is already good. Added a "black box" utility script that can return a code passed by argument, and/or crash if -c argument is specified.

Checklist

Tests

• [x] I added corresponding tests for bug fixes and new features. If possible, the tests fail without the changes
• [x] All new and existing tests are passing ($ tox -e py38; replace 38 by your Python version if necessary)

Documentation

• [ ] I have updated the relevant documentation related to my changes

Quality

• [x] I have read the CONTRIBUTING doc
• [x] My commits messages follow this format
• [x] My code follows the style guidelines ($ tox -e lint)

Further comments

n/a