ZODB tests fail in GitHub Actions on Python 3.8.6/macOS

I'm stumped with tests that fail only when using ZODB as a backend.

We are in the process of switching our automated build and tests from Travis-CI and Appveyor to GitHub Actions for all Pylons Project projects, including pyramid-cookiecutter-starter in this PR.

We have a matrix of builds across Ubuntu/macOS/Windows X py35/py36/py37/py38/py39/pypy3 X x86/x64. Only the one build on macOS/Python 3.8.6 fails, where 3 of the 9 tests fail. All 3 failing tests use ZODB for persistent storage. The build exits with the following error message.

subprocess.CalledProcessError: Command '['/private/var/folders/24/8k48jl6d249_n_qfxwsl6xvm0000gn/T/pytest-of-runner/pytest-0/test_zodb_jinja2_0/bin/python', '-m', 'pytest', '-q']' died with <Signals.SIGILL: 4>.

Installed Python packages and versions are identical between macOS/Python 3.8 and macOS/Python 3.9.

Whenever I run these same tests on my own macOS 10.15 machine and Python 3.8.0, they all pass. I doubt that there would be much of a difference between 3.8.0 and 3.8.6 to suddenly cause a failure like this, but it is possible.

The most likely cause would be somewhere in GitHub Actions.

I've exhausted my DuckDuckGo fu and searching various issue trackers for help.

I am reaching out in hope that someone has seen something similar with ZODB and has been able to resolve it. Any help appreciated. Thank you!

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