class ActionDispatch::Routing::RouteSet

def build_conditions(current_conditions, path_values)
  conditions = current_conditions.dup
  # Rack-Mount requires that :request_method be a regular expression.
  # :request_method represents the HTTP verb that matches this route.
  #
  # Here we munge values before they get sent on to rack-mount.
  verbs = conditions[:request_method] || []
  unless verbs.empty?
    conditions[:request_method] = %r[^#{verbs.join('|')}$]
  end
  conditions.keep_if do |k, _|
    k == :action || k == :controller || k == :required_defaults ||
      @request_class.public_method_defined?(k) || path_values.include?(k)
  end
end