public void disable_feature (Type feature_type)
This disables the actions of SessionFeatures with the given
feature_type (or a subclass of that type) on this, so that this is
processed as though the feature(s) hadn't been added to the session.
feature_type will disable Content-Type sniffing on the message.
You must call this before queueing this on a session; calling it on a message that has already been queued is undefined. In particular, you cannot call this on a message that is being requeued after a redirect or authentication.