Tried again and it applies without any problems.
I directly took version 2.2.1 from the server:
Code:
wget http://mesh.dl.sourceforge.net/sourceforge/ispconfig/ISPConfig-2.2.1.tar.gz
tar xzvf ISPConfig-2.2.1.tar.gz
cd install_ispconfig
patch -p1 < ../ISPConfig-2.2.1-MySQL-Quota.diff