fix(minifirewall): Properly detect old minifirewall versions

CHANGELOG.md

@@ -23,6 +23,7 @@ The **patch** part changes is incremented if multiple releases happen the same m
 * webapps/nextcloud: Set ownership and permissions of data directory
 * webapps/nextcloud: Add condition for config tasks
 * remount-usr: do not try to remount /usr RW if /usr is not a mounted partition
+* minifirewall: Fix nagios check for old versions of minifirewall
 
 ### Changed
 

minifirewall/files/check_minifirewall

@@ -87,7 +87,7 @@ main() {
           append_details "configuration is up-to-date"
           summary_ok "minifirewall is started and configuration is up-to-date"
         else
-          if echo "${check_result}" | grep --quiet --regexp 'usage'; then
+          if echo "${check_result}" | grep --ignore-case --quiet --regexp 'usage'; then
             append_details "minifirewall is too old to check active configuration"
           else
             case "${check_rc}" in