The `selectRep` documentation indicates that it choose the first
representation provided if no representation matches.
This was only partially correct, as `selectRep` required that no
representation matched **and** that the `Content-Type` header of the
response was empty.
This led to a problem because `defaultErrorhandler` relies on
`selectRep`, and when `selectRep` was unable to find a suitable
representation, it would "swallow" the original error that resulted in
`defaultErrorhandler` being called, and set a status 406 for all cases.
