Mac OS X Remote desktop client 10.7.2 and .3 cannot use websockets for gateway connections

The last two versions of the remote desktop client cannot use websockets for connections over a remote desktop gateway. Dissecting with Wireshark shows that the "upgrade" part of the protocol is not specified and thus the server falls back to legacy connections.

The release notes read "Improved compatibility with third-party network devices and load balancers for workspace download and RD Gateway-based connections.". Are websocket connections now deprecated? If so why? Can we re-enable websocket in the client? How?