@LordofTime sorry everything is explained http://askubuntu.com/questions/158909/how-to-patch-apache-mod-proxy-3-0-1-with-3-0-1-1-1-in-12-04, patch is already available. Apt-get provides old version and "$ dpkg -i *.deb" ends to iU -mode seen with `$ dpkg -l` i.e. not installed but unpacked.
Because I cannot understand how to do the manual installation, I put 11.10 Ubuntu to virtualbox until apt-get gets the patch in. No reason to stress :)