Direct from Valve:

Updates to Left 4 Dead 2 have been released. The updates will be applied automatically when your Steam client is restarted. The major changes include:

Left 4 Dead 2

• Fixed the localization sound caches
• Fixed AI tanks sometimes not getting assigned to human players
• Fixed exploit in C6M2 where players could jump through a gap in the fence
• Fixed commentary maps crashing on load

SDK

• Removed Perforce integration and Manifest UI when running Hammer under and SDK deployment
• Removed Version control menu for SDK

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