The reason is that there's cyclic dependency that must be avoided:
python -> tk -> libX11 -> libxcb -> xcb-proto -> python
Be careful when adding cyclic dependencies; xbps-src -N is your friend.
That addresses the following issues:
- Add tkinter ("Tk interface") support. Tkinter is the standard Python
binding to the Tk GUI toolkit.
- Fix broken IDLE (the Python IDE) built with Tkinter.
Add two new subpkgs: python-tkinter and idle-python.
