It looks like the USSG mirror messed something up, and all files previously on http://ftp.ussg.iu.edu/kde/ are now on http://ftp.ussg.iu.edu/kde/kde/, breaking our Mirrorbrain redirects. Either this changed very recently, or the rsync paths are still the same so "what files does the mirror have" still succeeds (otherwise Mirrorbrain would have noticed the files are gone and stopped redirecting there).
I suspect this is a mistake on their end (there's no double paths in any other thing they mirror), so rather than fix our HTTP path we should contact them to put the directory where it was. Disabling the mirror in the meantime may be a good idea though.