got installed from CD the ubuntu 8.0.4 with emc 2.3.0

Open my terminal and type this:
 sudo apt-get install git-core gitk git-gui
 git clone git://git.linuxcnc.org/git/emc2.git emc2-dev
 cd emc2-dev
 git branch --track v2_3_branch origin/v2_3_branch
 git checkout v2_3_branch
git checkout v2.4.6


then it say: "do you want to merge this bracnhe..."