osutils / _win32_pathjoin bytes / strings issues

I've managed to compile brz for windows, however, there remain some problems.

osutils.py code for windows (_win32_pathjoin, _win32_abspath, etc.) fails when called for brz init.

I've tracked this back to a couple of commits (6677.1.2 and 6677.1.1 'b-sprinkling') in bzr/working_tree_4 and dirstate.py although the issue is really the file / directory-handling in osutils and win32utils.

For example, _win32_joinpath() performs an ntpath.join() call but then tries to do a replace('\\', '/') which fails if a byte-string is passed as any of the arguments. The non-win32 version just uses os.path.join (lne 421 of osutils.py) without the attempted replace(). _