In this case, the check is actually supposed to be whether there is any path to be created after all once the `GIT_MKDIR_SKIP_LAST` flag has been taken into account. Due to that flag, it is possible that there is literally no directory to be created and the final verification should not be done. This happens in the test suite where we end up calling `git_futils_mkpath2file("filename", ...)` with a relative filename that doesn't have a leading directory at all.

That being said, I didn't notice that the below line that advances the tail past the `min_root_len` is not successfully preventing the mkdir on the root. Let me address that (and also make the "SKIP_LAST has left nothing to do" easier to understand).