sitecustomize.py not imported in a virtual environment

[Роман Донченко]

This is on Ubuntu 22.04, python3==3.10.4-3.

Run this:

$ python3.10 -mvenv ./venv
$ echo 'print("In sitecustomize.py")' > ./venv/lib/python3.10/site-packages/sitecustomize.py
$ ./venv/bin/python -c ''
[nothing]

Expected output:

In sitecustomize.py

The reason this doesn't work is that the python3 package contains its own sitecustomize module (at /usr/lib/python3.10/sitecustomize.py) whose job is to initialize the Apport exception hook, and /usr/lib/python3.10 is listed before ./venv/lib/python3.10/site-packages in the default sys.path.

I think the best way to fix this would be to:

1. Remove /usr/lib/python3.10/sitecustomize.py from libpython3.10-minimal

2. Add /usr/lib/python3/dist-packages/apport.pth with the following contents to python3-apport:

   import apport_python_hook; apport_python_hook.install()

This would have the same effect as the current sitecustomize.py, but would not conflict with user-provided sitecustomize modules.

Alternatively, /usr/lib/python3.10/sitecustomize.py could simply be moved to /usr/lib/python3.10/dist-packages, which would also fix the problem. A disadvantage of this approach is that a user-defined /usr/local/lib/python3.10/dist-packages/sitecustomize.py file would override it and disable the Apport hook.