Preemptive digest auth is broken

[slandelle]

See disabled tests in AuthTimeoutTest.

[bahrmichael]

This was resolved with 79016a7.

[slandelle]

Nah, the failing test is still disabled :(

[bahrmichael]

TIL there a n+1 ways to disable a test.

[slandelle]

Anyway, I think preemptive digest auth doesn't make any sense: I don't think the client can possibly know the nonce beforehand.
Except if someone provide information showing preemptive digest auth makes sense, it will be dropped in a future version.