I figured out when you also use the minor Release number as 7.2.1511 the script is not downloading LiveOS folder. Could you also add this fix for Minor releases.
python mkelfs.py --release 7 --arch x86_64 -o centos -b CentOS 7 x86_64 --target /var/satellite/iso-images/
Is donwloading the LiveOS folder
Like reported in closed issue #13: