only try to remove munin-async if it's installed (less noise when deploying)

Signed-off-by: Holger Levsen <holger@layer-acht.org>

update_jdn.sh

@@ -621,8 +621,9 @@ if [ -f /etc/debian_version ] ; then
 	fi
 fi
 
+# remove munin-async (if it's installed which happens during setup as it's a recommends)
 # harmless but has a service which can fail and thus can make maintenance jobs unstable
-sudo apt-get remove munin-async
+( dpkg -l munin-async 2>/dev/null && sudo apt-get remove munin-async ) || true
 
 #
 # deploy package configuration in /etc and /usr