Support per-project Python versions in Docker with safe compile wrapper

[Sonzakir]

Summary

• This PR updates the BugsInPy Docker workflow so checked-out projects are compiled with the Python version declared by their own BugsInPy metadata instead of always using the Docker image’s default Python.

• Previously, the Docker image was based on Python 3.12. That caused many BugsInPy projects to fail during compilation because their dependencies were pinned for older Python versions, usually in the 3.6-3.8 range. For example, some old dependencies try to build C extensions that are no longer compatible with Python 3.12, so compilation fails before the actual buggy project can even be tested.

What changed:

• Replaced the fixed python:3.12-slim-trixie base image
• Added pyenv to the Docker image so multiple Python versions can be installed and selected inside one container.
• Removed pre-installation of project Python versions during Docker build.
• Python versions are now installed lazily, only when a checked-out project is compiled.
• Added a new wrapper script: bugsinpy-safe-compile.
  • The wrapper reads the required Python version from the current checkout’s bugsinpy_bug.info.
  • It sets the checkout-local Python version using .python-version.
  • It then runs the existing bugsinpy-compile command.
• This helps projects like old black versions generate/import package metadata correctly.

Why this is useful:

• One container can compile projects requiring different Python versions.
  • Projects with the same Python version but conflicting dependencies are still isolated because bugsinpy-compile creates a separate env virtual environment inside each checked-out project.
• The existing BugsInPy scripts remain mostly untouched; this PR adds a safer wrapper around the existing compile behavior.
• The Docker image builds faster because it no longer compiles Python version during image build.

Example usage

bugsinpy-checkout -p black -i 1 -v 0 -w /home/workspace/black-bug1
cd /home/workspace/black-bug1/black
bugsinpy-safe-compile
bugsinpy-test