Route "/" below branch route doesn't work (returns 404)

Klein version 17.10.0

In the following example program (adapted from an example from another issue) I'm trying to get the route /users/ to return a list of all users.

Retrieving http://localhost:8123/users/123 works as expected, returning A User Named "123"..

Retrieving http://localhost:8123/users redirects to http://localhost:8124/users/, which returns a 404 Not Found error. I would expect it to return All users!.

Is this expected behavior?

from klein import route, run, Klein

class UsersApp(object):
    routes = Klein()

    # This route doesn't seem to work: results in a 404 Not found error
    @routes.route("/")
    def all_users(self, request):
        request.setHeader('content-type', 'text/plain')
        return 'All users!'

    @routes.route("/<string:username>")
    def an_user(self, request, username):
        request.setHeader('content-type', 'text/plain')
        return 'A User Named "{username}".'.format(username=username)

class MathApp(object):
    mathroutes = Klein()
    @mathroutes.route("/add/<int:a>/<int:b>")
    def add(self, request, a, b):
        return str(a + b)


@route("/users", branch=True)
def users_app(request):
    return UsersApp().routes.resource()

@route("/math", branch=True)
def math_app(request):
    return MathApp().mathroutes.resource()

@route("/")
def hi(request):
    return "Hi"

run("localhost", 8124)

Decorating all_users with @routes.route("") results in an error ('urls must start with a leading slash').

Start by running the supplied Klein 17.10.0 example and trace how the branch route at /users delegates to UsersApp().routes.resource(). Check the route handling for / and /string:username; done means /users/ returns "All users!" while /users/123 continues to return the named-user response without a 404.