I'm using the Debian/lenny packages of trac (0.11.1-2.1) and trac-git (0.0.20080710-3) for the Trac instance at http://serviceplatform.org:8000/trac/browser/admin.
Browsing most directories work fine. However, there are some like the prepared "testarea" subdirectory which contain non-ASCII filenames encoded in UTF-8. I see some mention of unicode() in the GitPlugin files but cannot really see where the fix would belong.
This is the error message in case the site is unreachable:
Trac detected an internal error:
UnicodeDecodeError?: 'ascii' codec can't decode byte 0xd1 in position 15: ordinal not in range(128)