With 8.2.0, attempt to import docs from niece module fails

This issue is perhaps one of the weirdest and most obscure I've seen. My investigation began in jaraco/jaraco.xonsh#1. The summary is this:

• In GitHub actions (only), during collection, when attempting to collect docs/conf.py, something outside the call stack attempts to import jaraco.xonsh.docs, even though jaraco.xonsh is a module and docs is a sibling of jaraco.
• The issue is present in multiple Python versions (at least 3.10-3.12).
• The issue does not replicate when testing locally (either in a Linux Docker container or in macOS).
• The issue does replicate when using act to simulate the GitHub actions using Docker.
• Pinning to pytest<8.2 suppresses the failure.
• Disabling the xonsh plugin suppresses the failure.
• Note that jaraco.xonsh is a xonsh module in a PEP 420 namespace.
• Importing jaraco.xonsh might not be problematic except:
  • xonsh itself has a pytest plugin that configures subprocesses to raise on error
• The jaraco.xonsh module hasn't been collected or tested (in earlier runs or with pytest 8.2 when it passes locally).

As you might imagine, creating a minimal example is near impossible given the peculiarities of this scenario. The jaraco.xonsh project is nearly a minimal example in itself. The easiest way to replicate the issue is to clone the project at 249226010f9c9e5490dab851947efba2dceecb63, install act, and run the command in https://github.com/jaraco/jaraco.xonsh/issues/1#issuecomment-2084576106.

Questions for which I'm hoping to find answers:

• What is it about GHA that the issue only occurs there?
• What is it that's trying to import jaraco.xonsh.docs and why doesn't it show up in the stack trace?
• What's new in pytest 8.2 that would trigger this behavior?
• How is it that collecting "docs/conf.py" would ever try to import "jaraco.xonsh.docs"?

Start by cloning jaraco.xonsh at commit 249226010f9c9e5490dab851947efba2dceecb63 and running the command in the linked issue comment with act. Compare pytest 8.2 with pytest<8.2 while collecting docs/conf.py and the xonsh plugin is enabled. Done means explaining the unexpected jaraco.xonsh.docs import and identifying a fix for the collection failure.