class Sprockets::Manifest

def backups_for(logical_path)

assets mtime in descending order (Newest to oldest).
version is always excluded. The return array is sorted by the
Finds all the backup assets for a logical path. The latest 
def backups_for(logical_path)
  files.select { |filename, attrs|
    # Matching logical paths
    attrs['logical_path'] == logical_path &&
      # Excluding whatever asset is the current
      assets[logical_path] != filename
  }.sort_by { |filename, attrs|
    # Sort by timestamp
    Time.parse(attrs['mtime'])
  }.reverse
end