remove site.py files

setuptools site.py can't resolve recursively which is needed for nix,
as each package has its own directory. A different solution than
putting the loader into every package output needs to be found.

see also #209

pkgs/development/python-modules/generic/default.nix

@@ -82,9 +82,7 @@ python.stdenv.mkDerivation (attrs // {
     # Remove any site.py files generated by easy_install as these
     # cause collisions. If pth files are to be processed a
     # corresponding site.py needs to be included in the PYTHONPATH.
-    #
-    # leave them until we have a better solution: see #209
-    #rm -f "$out/lib/${python.libPrefix}"/site-packages/site.py*
+    rm -f "$out/lib/${python.libPrefix}"/site-packages/site.py*
 
     ${postInstall}
   '';