200 OK / HTML content type / empty response body when returning None from a branch route

In the following Klein application:

from klein import route, run

@route("/something", branch=True, strict_slashes=False)
def something(request):
    return None

run("localhost", 8080)

Then GET /something/else will result in a 200 OK with no content.

In fact, GET /something/ and GET /something have the same behavior, unless you set strict_slashes=True, in which case only GET /something/ will return a 404 (GET /something/else and GET /something still return 200s even with strict_slashes=True).

This seems off to me; a None ought to be 404s all around.

Start by running the minimal Python Klein application in the issue and requesting /something, /something/, and /something/else with both strict_slashes settings. Read the branch-route handling responsible for None responses and add regression coverage; done means these unmatched requests consistently return 404 rather than 200 with an empty body.