TestSyncWithTrackRenames failing with new pixeldrain backend

@ncw In this thread you say:

rclone doesn't maintain permissions or ownership as it isn't a concept which maps to cloud storage.

I don't really agree with that. File permissions are fundamental properties of a file, just like the file's name, create/mod-time and size. Every other sync tool for Linux can preserve file permissions. Omitting file permissions means that it is not possible to create a full backup of your system as all the executables will stop working. Copying a git repo to the cloud is also not possible as most git repos depend heavily on permissions. These are really important use cases!