HttpAuth middleware incorrectly handles Authorization header

[JamesFysh-alliance]

This line:

(method, authentication) = authorization.split(' ', 1)

in src/allianceutils/middleware/http_auth.py makes the assumption that the Authorization header will contain a space character. If it does not, a ValueError is raised, along the lines of ValueError: not enough values to unpack (expected 2, got 1).

The problem with this is that we wind up with a 500 server error response as the uncaught exception propagates. It might be better to detect this scenario and explicitly return a 401 (eg. call return self.__unauthorized()). Or maybe not, that could actually make it harder to debug.

I ran into this because I have a client application trying to make an API call, and that application uses the Authorization header itself, which causes a conflict when HTTP Basic Auth is also enabled.

[davecoates]

I think returning a 401 is correct, but we could also log a warning that the authorization header is invalid if it doesn't contain a space to assist with debugging