Admin: Fix configuration variable recuperation for none multiURL plateforms -refs BT#20531

main/inc/lib/api.lib.php

@@ -9090,7 +9090,7 @@ function api_get_configuration_value($variable)
                 // Try to found element with id = 1 (master portal)
                 if (array_key_exists(1, $_configuration[$variable])) {
                     return $_configuration[$variable][1];
-                } else {
+                } elseif (api_is_multiple_url_enabled()) {
                     // The value was there for other URLs but not the main URL nor the current URL
                     return null;
                 }