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If you type the id(k)fa cheat and then drop the weapon you're holding, you don't switch to the best available weapon, but instead are unable to use any weapon until your weapon inventory is reset somehow (idclev, dying in singleplayer or in coop with the lose weapons dmflag, etc.).

Probaly gonna get "Don't do that!"

I should mention that this also happens if the weapon is taken away through (A_)TakeInventory, which was how I noticed it in the first place.

fixed