The CopyDir() call will fail on filesystems that do not support extended attributes. This is because the function will eventually call sysx.LListxattr(), which will return ENOTSUP. This shouldn't be a problem for normal operations, as it just means there are no xattrs to copy, but as it's still an error it will say the function call failed.

This can be mitigated by attaching an XAttrErrorHandler to the CopyDir function call, but this being default behavior seems to be a bug.