SteamDB: SDK "multiplayerfix" ?

Besides the on-going "Bison" work, I found something new today:
http://steamdb.info/app/16830/#section_history

There's a non-public update to the SDK. The name of the branch is "multiplayerfix."
It has a build ID of 161068 vs the public release's 134269.

Maybe someone with experience with the SDK could explain why it could need a multiplayerfix? All that's occurring to me is allowing mods to be enabled in multiplayer.

If you don't see why multiplayer needs fixing, you simply need to try multiplayer
Oops... did not notice it was about SDK, not game.