From the hlds_linux mailing list:
We have released an update that rolls back the Counter-Strike: Source changes made in this last update (apart from the de_inferno changes). You need to run hldsupdatetool to get this update.
which was a reply to the message:
We have released an update to Counter-Strike: Source and the Source engine. Run the hldsupdatetool to get this update.
Testing and quality control. Yeah. Right.