Python virtual environment smoke tests on SRD

[dsj976]

✅ Checklist

• I have searched open and closed issues for duplicates.
• This is a problem observed when managing a Data Safe Haven.
• I can reproduce this with the latest version.
• I have read through the documentation.
• This isn't an open-ended question (open a discussion if it is).

💻 System information

• Data Safe Haven version: 4.2.0
• Operating system details: macOS

🌵 Powershell module versions

🚫 Describe the problem

This is an issue encountered when running smoke tests in the SRD. When bats run_all_tests.bats is run, the Python virtual environment tests pass, but when this test is run individually (by running test_virtual_environments_python.sh), the first check seems to fail:

🚂 Workarounds or solutions

[jemrobinson]

This test runs which pyenv. What happens when you run that on its own? What's the return value (run echo $? straight afterwards).