Adam Wick
fbd98a5f9b
The prior implementation involved some (moderately awkward) layered `match` expressions; this version skips those in favor of `?`. The cost is a little less detail about (for example) when serialization errors happen. On the bright side, it gains us some huge improvements in code clarity. We might be able to get back the tracing later, with other library support. In addition, we know have a couple tests: one to make sure we choose the authentication method appropriately, and a very basic handshake test for when we're not actually negotiation a username and password.