ubuntu 18: systemd kill ends up killing the script itself

This is because KillMode=control-group by default

(cherry picked from commit c07c8b5bb8)

src/scripts/restartservice.sh

@@ -35,9 +35,13 @@ elif [[ "${service}" == "docker" ]]; then
 elif [[ "${service}" == "collectd" ]]; then
     systemctl restart --no-block collectd
 elif [[ "${service}" == "box" ]]; then
-    # ExecReload does not work on ubuntu 18
-    # systemctl reload --no-block box
-    systemctl kill --signal=SIGHUP box
+    readonly ubuntu_version=$(lsb_release -rs)
+    if [[ "${ubuntu_version}" == "18.04" ]]; then
+        pid=$(systemctl show box -p MainPID | sed 's/MainPID=//g')
+        kill -HUP $MAINPID
+    else
+        systemctl reload --no-block box
+    fi
 else
     echo "Unknown service ${service}"
     exit 1