Add possibility to inherit DEBUG value

cluster/disable.host.queue.sh

@@ -5,7 +5,8 @@ readonly PROGNAME=$(basename "${0}")
 readonly PROGDIR=$(readlink -m $(dirname "${0}"))
 readonly ARGS="${*}"
 readonly NBARGS="${#}"
-readonly DEBUG=1
+## Test if DEBUG is already defined (by parent script,…)
+[ -z "${DEBUG}" ] && readonly DEBUG=1
 
 ## Colors
 readonly PURPLE='\033[1;35m'