Virtual environments created with `venv --system-site-packages` can't access binaries from pre-installed packages, neither re-install those packages

Bug report

Bug description:

I wanted to "pre-install" in my "source" python installation some packages I often use, so that those packages are readily available in the virtual environments created from this "source", without wasting space and time re-installing them every time I create a new venv.

I thought the --system-site-packages would do just that, however, this "doesn't work" for binaries installed by python packages (for instance, ipython, but I can think of other cases like pylint, flake8 or cookieninja):

I create the venv (using a locally compiled 3.11 version):

bli@latimeria:~/tmp$ ~/python3.11/bin/python3 -m venv --system-site-packages .venv
bli@latimeria:~/tmp$ source .venv/bin/activate

However, the bin directory of the venv does not contain ipython:

(.venv) bli@latimeria:~/tmp$ ls .venv/bin/ | grep ipython

But ipython is installed in the source python 3.11:

(.venv) bli@latimeria:~/tmp$ ls ~/python3.11/bin/ | grep ipython
ipython
ipython3

This is however not in the PATH when in the venv (in this particular case, calling ipython starts one installed with python 3.6 in ${HOME}/bin, whereas if I try with a package not installed anywhere else than in the python 3.11 install, like cookieninja, the command is not found).

This even prevents the installation of ipython in the venv:

(.venv) bli@latimeria:~/tmp$ .venv/bin/pip3 install ipython
Requirement already satisfied: ipython in /home/bli/python3.11/lib/python3.11/site-packages (8.24.0)
[...]
(.venv) bli@latimeria:~/tmp$ .venv/bin/pip3 install --upgrade ipython
Requirement already satisfied: ipython in /home/bli/python3.11/lib/python3.11/site-packages (8.24.0)
[...]

CPython versions tested on:

3.11

Operating systems tested on:

Linux

Reproduisez le problème avec python -m venv --system-site-packages, l’activation et des paquets tels que ipython ou cookieninja installés dans le Python source. Comparez le PATH du venv et le comportement de pip install ou de la mise à niveau ; la tâche est terminée lorsque l’accès attendu aux binaires des paquets préinstallés et le comportement d’installation des paquets sont vérifiés.