Looking into the project im working on I discovered why relpath was acting strangely.

It is because the project mocks get_cwd but not get_cwdu. Your request helped me track that down :-)

So that is not an issue. However, the issue described in the original ticket definitely happens in a clean python shell.

I still think it is bad that the method sometimes returns str and sometimes returns unicode, but I see your point that ultimately the byte strings that do come out of here coerce into unicode cleanly.

Thanks for working though this with me.