Currently, the function is documented to return a string:
https://docs.python.org/dev/library/locale.html#locale.strxfrm
"Transforms a string to one that can be used in locale-aware comparisons."

The problem is that we don't have enough developers who care of Solaris/Illimios to fix these issues (propose patches).

test_locale is just *one* example. The curses module is broken for years on Solaris if I recall correctly...