Before this change, if a directory was renamed and it or any children
had virtual entries in it they weren't flushed.
The consequence of this was that the directory path got out sync with
the actual position of the directory in the tree, leading to listings
of the old directory rather than the new one.
The fix renames any directories remaining after the ForgetAll to have
the correct path which fixes the problem.
See: https://forum.rclone.org/t/after-a-directory-renmane-using-mv-files-are-not-visible-any-longer/22797