vagrant-dev : in bootstrap.sh, the DEBUG variable don't works.

in Vagrant/.../bootstrap.sh, the following code don't works.

# If you set DEBUG on true, you will install all the environment to allow unit tests to play.
declare DEBUG=false

if [[ "${DEBUG}" ]]; then
     echo "===== Adding phpinfo.php"
     echo "<?php phpinfo();" >"${COMPTOIR_DIR}/webroot/debug_phpinfo.php"
fi
# ---> the "${COMPTOIR_DIR}/webroot/debug_phpinfo.php" file is always added

see: https://unix.stackexchange.com/questions/105935/understanding-boolean-operators-in-bash-script