Comment 1 for bug 942603

That bothered me, too. This happens resulting from a well-known problem for Turkish locale. Lower 'i' stays as 'i' on upper() function, so 'assign' becomes 'ASSiGN' instead of 'ASSIGN' and that causes further error when getattr(node, 'ASSiGN') is called. I don't know what upper() is used for. But you should either accept this workaround or use locale.setlocale(locale.LC_ALL, 'en_US.UTF-8') at the top of the code somewhere as upper() and lower() functions are locale-dependent.