Now we are ready to change the packages and develop on the system.
First of all, cd into your IPFire-3.x git directory. In the next step prepare a branch with a useful name.
git branch grep-2.24 -t origin/master
After creating a new branch, check it out:
git checkout grep-2.24
Now you just have to go into the desired folder and make your changes to the .nm file. See Packaging Guidelines (for IPFire 3.x) for details.