When URL_PATH is blank, it should assume that it is '/'

Closes #2908

CHANGELOG

@@ -37,6 +37,7 @@ Cacti CHANGELOG
 -issue#2903: PHP recommendations can generate a warning causing json issues
 -issue#2905: Sorting plugins by version can lead to unexpected ordering
 -issue#2907: SSL column for multiple pollers can be incorrectly set causing SQL errors
+-issue#2908: When URL_PATH is blank, it should assume that it is '/'
 
 1.2.5
 -issue#1978: Popup Menus can appear off screen when using Graph Thumbnails

include/global.php

@@ -137,6 +137,11 @@ if (!empty($db_missing_vars)) {
 	die("config.php is $db_missing_vars" . PHP_EOL);
 }
 
+if (empty($url_path)) {
+	/* define default url path */
+	$url_path = '/';
+}
+
 /* set the local for international users */
 setlocale(LC_CTYPE, 'en_US.UTF-8');