I posted another question asking for comment about using iPython together with virtual environments, and ran into a related strange issue.
My system is running Arch Linux and I believe all Python packages on this system were [url=https://pastebin.com/0K4pGRLv]installed
using the Arch Linux package manager `pacman`[/url] (positive all the major ones).
Comparing the output of `pip freeze`:
1) I did a `pip freeze` of my [URL=https://pastebin.com/meaUx6AN]current
install of Python from Arch packages[/URL].
2) Created a virtual environment, venv
`$mkvirtualenv --system-site-packages venv`
Used the `--system-site-packages` argument to use the Arch base Python packages.
3) Compared a second `pip freeze` [URL=https://pastebin.com/3ytmPFPE]from
inside the active venv[/URL].
I expected the diff to be the same (except for the one package I installed with pip, python-magic), but there are [url=https://pastebin.com/v0Nvr8CQ]numerous
What are some of the reasons a new VENV not have the same modules when using site packages argument?
For what reasons might the venv not have the same packages?