debian: don't start hobo-agent if policy-rc.d says so (#14724)

debian/hobo-agent.postinst

@@ -18,8 +18,18 @@ case "$1" in
     # ensure dirs ownership
     chown $USER:$GROUP /var/log/$NAME
 
-    supervisorctl reread
-    supervisorctl restart hobo-agent
+    set +e
+    START_HOBO_AGENT=1
+    if [ -x /usr/sbin/policy-rc.d ]; then
+      /usr/sbin/policy-rc.d
+      RETVAL="$?"
+      if [ $RETVAL != 0 ]; then START_HOBO_AGENT=0; fi
+    fi
+    set -e
+    if [ $START_HOBO_AGENT = 1 ]; then
+      supervisorctl reread
+      supervisorctl restart hobo-agent
+    fi
   ;;
 
   abort-upgrade|abort-remove|abort-deconfigure)