From 6ec7e639cc7c9a3b38c7ac28e532793f347c41d9 Mon Sep 17 00:00:00 2001
From: CiviCRM <info@civicrm.org>
Date: Mon, 21 Dec 2015 15:10:16 -0800
Subject: [PATCH] CRM_Core_Config::customCSSURL - Don't tample empty values

Ex: The 4.4 upgrader checks `customCSSURL` and sets `disable_core_css`
depending on whether the value is empty.  Since the addTrailingSlash was
converting empty to '/', this caused bad upgrades.
---
 CRM/Core/Config/MagicMerge.php | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/CRM/Core/Config/MagicMerge.php b/CRM/Core/Config/MagicMerge.php
index 57bf9c9c0f..884a65a25d 100644
--- a/CRM/Core/Config/MagicMerge.php
+++ b/CRM/Core/Config/MagicMerge.php
@@ -233,7 +233,10 @@ class CRM_Core_Config_MagicMerge {
       case 'setting-url-abs':
       case 'setting-url-rel':
         $type = (strstr($type, 'abs')) ? 'absolute' : 'relative';
-        $value = CRM_Utils_File::addTrailingSlash($this->getSettings()->get($name));
+        $value = $this->getSettings()->get($name);
+        if ($value) {
+          $value = CRM_Utils_File::addTrailingSlash($value);
+        }
         $this->cache[$k] = Civi::paths()->getUrl($value, $type);
         return $this->cache[$k];
 
-- 
2.25.1