mirror_file (Merb::Slices::ModuleMixin)

    # File lib/merb-slices/module_mixin.rb, line 468
          def mirror_file(source, dest, copied = [], duplicated = [], postfix = '_override')
            base, rest = split_name(source)
            dst_dir = File.dirname(dest)
            dup_path = dst_dir / "#{base}#{postfix}.#{rest}"
            if File.file?(source)
              FileUtils.mkdir_p(dst_dir) unless File.directory?(dst_dir)
              if File.exists?(dest) && !File.exists?(dup_path) && !FileUtils.identical?(source, dest)
                # copy app-level override to *_override.ext
                FileUtils.copy_entry(dest, dup_path, false, false, true)
                duplicated << dup_path.relative_path_from(Merb.root)
              end
              # copy gem-level original to location
              if !File.exists?(dest) || (File.exists?(dest) && !FileUtils.identical?(source, dest))
                FileUtils.copy_entry(source, dest, false, false, true)
                copied << dest.relative_path_from(Merb.root)
              end
            end
          end