Check_MK Werk 7215: Avoid duplicate services for if_fortigate check

ID: 7215 Title: Avoid duplicate services for if_fortigate check Component: Checks & agents Level: 1 Class: Bug fix Version: 1.6.0i1 This fixes the duplicate services warning displayed on the discovery page for if/if_fortigate checks. Services of the if checkplugin are no longer discovered if the if_fortigate plugin already found interfaces.