The same occurs on Windows - trying to update Dota 2 it eats up 3 Gb of disk, fails, and doesn't cleanup. Now I've less than 100 Mb on my drive, a quick search on Steam settings show no option to clean this mess, and there is no space to install the TikiOne Steam Cleaner (http://www.ghacks.net/2013/01/22/free-disk-space-by-cleaning-the-steam-folder/) to clean it.
I just can't believe anyone is able to put a software with such abyssal flaw into production.
Nothing extracted yet.
Steam doesn’t check for disk free space before downloading an update - or if it does and it only considers the download size, not the size required to patch the game files (which was about 2GB for the game in question).
Noticed this with the HL2 update, even though its just downloading 48MB or something, it makes temp files inside downloading/ of a bunch of vpk files, prints out an assertion error when disk is full and stops the download - the disk will now sit at 4K free which can cause other problems :(
User has to delete the files themselves or clear enough space for the update to continue.
Cannot confirm on Windows, maybe an issue there as well.