See #490 discussion.
This reverts commit 1278859d31, reversing
changes made to 0c020c98f9.
Conflicts:
pkgs/desktops/xfce/core/xfce4-session.nix (take master)
pkgs/lib/misc.nix (auto)
http://bugs.python.org/issue15833
When Python 3.3.0 attempts to compile python bytecode in the system
directories it raises and exception and stops. Since Python 3.3 is
only required by the latest Blender, I hope it's OK to use the RC
until the final release.