Fix a potential issue with updating interfaces (#50464)

lib/ansible/modules/remote_management/cobbler/cobbler_system.py

@@ -297,11 +297,11 @@ def main():
                     if key not in IFPROPS_MAPPING:
                         module.warn("Property '{0}' is not a valid system property.".format(key))
                     if not system or system['interfaces'][device][IFPROPS_MAPPING[key]] != value:
+                        result['changed'] = True
                     interface_properties['{0}-{1}'.format(key, device)] = value
 
-            if interface_properties:
+            if result['changed'] is True:
                 conn.modify_system(system_id, "modify_interface", interface_properties, token)
-                result['changed'] = True
 
         # Only save when the entry was changed
         if not module.check_mode and result['changed']: