Unless I'm very much mistaken, this is another instance of the old Cocoa Tk problem documented here (http://sourceforge.net/p/tktoolkit/bugs/2722/) and referred to in https://www.python.org/download/mac/tcltk/.  It's not like a normal TclError in that it causes the embedded Tcl interpreter used by Python to hard crash with no chance of recovery.  This is why we strongly recommend people not use older versions of Cocoa Tk as, unfortunately, are still shipped by Apple with the latest versions of OS X.  The problem has been fixed in more recent versions of Cocoa Tk such as those shipped by ActiveState and which the python.org installer will use if installed (and will warn about if not installed).