pub fn undo(source: &Path, backup_dir: &Path, count: usize) -> Result<()>Expand description
Restore the doing file from the Nth most recent unconsumed backup (1-indexed).
Before restoring, a consumed snapshot of the current source is created so
that redo can reverse the undo. The restored backup and all newer backups
are also marked as consumed (renamed from .bak to .undone) so that
subsequent calls walk backwards through history. Returns an error if fewer
than count unconsumed backups exist.