This is just inherently not a determinisitc test. We don't use the log HTTP
interface any more, so it can just go. A more radical "solution" is inbound
shortly.
Fixes#1207
This commit introduces MultiDict, a multi-dictionary similar to
ODict, but with improved semantics (as in the Headers class).
MultiDict fixes a few issues that were present in the Request/Response
API. In particular, `request.cookies["foo"] = "bar"` has previously been a
no-op, as the cookies property returned a mutable _copy_ of the cookies.