`pip install`ing PyYAML crashes the Action running

Describe the bug pip installing a version of PyYAML which is not the version being used to run the workflow causes the workflow runner to crash on subsequent steps.

2020-07-15T21:47:13.5356959Z FileNotFoundError: [Errno 2] No such file or directory: '/opt/hostedtoolcache/Python/3.7.8/x64/lib/python3.7/site-packages/PyYAML-5.3.1-py3.7-linux-x86_64.egg'
2020-07-15T21:47:13.5916339Z ##[error]Process completed with exit code 1.

Which version of the action are you using?

• v1
• v2
• Some other tag (such as v2.0.1 or master)

Environment

• self-hosted
• Linux
• Windows
• Mac

If applicable, please specify if you’re using a container

Python Versions 3.7.8

To Reproduce Steps to reproduce the behavior:

1. Run a workflow e.g. this one that pip installs some version of PyYAML
2. On my workflow, scroll down to “Install Conflicting PyYAML”
3. Notice the FileNotFoundError which is not from execution of my workflow.
4. Notice that the “Do Something Else” step is not run.

Run/Repo Url https://github.com/jameshiebert/action/runs/875331441?check_suite_focus=true

Additional context I guess the right (?) way to work around this is to install everything in a virtual environment (as shown in the following commit), but:

1. There’s nothing in the README (that I can find, at least) that says this is necessary, and
2. I’d argue that it’s a bug (or at the very least, not proper encapsulation) if the user is able to cause the workflow runner to crash.

If I’m doing something wrong, I’d be happy to hear about it 😃 Thanks.

[maxim-lobanov]

Hello everyone, this issue is related to image, not the setup-python task. We are working on investigation and fix. Progress can be tracked in https://github.com/actions/virtual-environments/issues/1202#issuecomment-660006490

[nathan-weinberg]

I was able to workaround this by changing the pyyaml version from 5.1 to 5.3.1 in my requirements.txt