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

使用 python -m venv --system-site-packages、啟用操作，以及安裝在來源 Python 中的 ipython 或 cookieninja 等套件重現此問題。比較 venv PATH 和 pip install 或升級行為；驗證了對預先安裝套件二進位檔的預期存取權限以及套件安裝行為後，即表示完成。