> It works correctly in Python 3.2.3 64-bit on Windows 8.

Can you reproduce the issue on other Windows versions?

2013/2/7 Jan Lachnitt <report@bugs.python.org>:
>
> Jan Lachnitt added the comment:
>
> Knowing that the problem is related to the internal representation of the strings, I have written a short script which reproduces the problem. It is this simple:
>
> import os
> name = 'sub-fcc'
> wrkdir = 'D:\\Bug reports\\Python\\test'
> dirname = wrkdir+os.sep+name
> print(dirname)
> print(ascii(dirname.encode("unicode_internal")))
> dirname += os.sep+'bulk'
> print(dirname)
> print(ascii(dirname.encode("unicode_internal")))
>
> Output:
>
> D:\Bug reports\Python\test\sub-fcc
> b'D\x00:\x00\\\x00B\x00u\x00g\x00 \x00r\x00e\x00p\x00o\x00r\x00t\x00s\x00\\\x00P\x00y\x00t\x00h\x00o\x00n\x00\\\x00t\x00e\x00s\x00t\x00\\\x00s\x00u\x00b\x00-\x00f\x00c\x00c\x00'
> D:\Bug reports\Python\test\sub-fcc\bulk
> b'D\x00:\x00\\\x00B\x00u\x00g\x00 \x00r\x00e\x00p\x00o\x00r\x00t\x00s\x00\\\x00P\x00y\x00t\x00h\x00o\x00n\x00\\\x00t\x00e\x00s\x00t\x00\\\x00s\x00u\x00b\x00-\x00f\x00c\x00c\x00\x00\x00\x00\x00\xd8\xa3\x90\x02\x00\x00'
>
> The end of the output varies from run to run.
>
> It works correctly in Python 3.2.3 64-bit on Windows 8.
>
> ----------
>
> _______________________________________
> Python tracker <report@bugs.python.org>
> <http://bugs.python.org/issue17137>
> _______________________________________