Fix venv creation in Python environments

The way we build python environments is subtly broken. A python
environment should be semantically identical to a vanilla Python
installation in, say, /usr/local. The current implementation, however,
differs in two important ways. The first is that it's impossible to use
python packages from the environment in python virtual environments. The
second is that the nix-generated environment appears to be a venv, but
it's not.

This commit changes the way python environments are built:

  * When generating wrappers for python executables, we inherit argv[0]
    from the wrapper. This causes python to initialize its configuration
    in the environment with all the correct paths.
  * We remove the sitecustomize.py file from the base python package.
    This file was used tweak the python configuration after it was
    incorrectly initialized. That's no longer necessary.

The end result is that python environments no longer appear to be venvs,
and behave more like a vanilla python installation. In addition it's
possible to create a venv using an environment and use packages from
both the environment and the venv.

1 files changed, 0 insertions, 3 deletions

diff --git a/pkgs/development/interpreters/python/pypy/default.nix b/pkgs/development/interpreters/python/pypy/default.nix
index c64c65df350e..c11ca7330c2c 100644
--- a/pkgs/development/interpreters/python/pypy/default.nix
+++ b/pkgs/development/interpreters/python/pypy/default.nix
@@ -126,9 +126,6 @@ in with passthru; stdenv.mkDerivation rec {
     ln -s $out/${executable}-c/include $out/include/${libPrefix}
     ln -s $out/${executable}-c/lib-python/${if isPy3k then "3" else pythonVersion} $out/lib/${libPrefix}
 
-    # Include a sitecustomize.py file
-    cp ${../sitecustomize.py} $out/${if isPy38OrNewer then sitePackages else "lib/${libPrefix}/${sitePackages}"}/sitecustomize.py
-
     runHook postInstall
   '';