It is set in the DAMASK root folder by running damask_env.sh
Much needed in the testing routines so far (try ./testing/run_tests.py)
damask_env.sh could also trigger other scripts to get to a working setup after fresh checkout. For example it could run
./processing/setup/setup_processing.py
./code/setup/setup_code.py
if it finds that we have a fresh checkout.