So basically, the updated version of the patch fixes some of the issues it brought (see details here: Security Patch SUPEE-7405 - possible problems?)
The SUPEE-7405 v 1.1 patch bundle includes the following:
Cart Merge Patch (SUPEE-7978)
Carts with identical items now merge correctly. Previously, when a
cart with one item was merged with another cart that contained the
same item, Magento did not merge the cart totals correctly. The cart
now includes only one item, and the total is correct.
SOAP API Patch (SUPEE-7822)
The Magento SOAP API now works as expected. Previously after
installing the SUPEE-7405 v1.0 patch, an API request would cause a 500
error, and Magento would log an exception.
PHP 5.3 Compatibility (SUPEE-7882)
The patch was not compatible with PHP 5.3 for earlier versions of
Magento that were still supporting this version. Merchants
experiencing this issue were unable to view sales information in the
Upload File Permissions
The patch restores less restrictive file permissions (0666 for files
and 0777 for directories) as more strict permissions introduced by the
original SUPEE-7405 patch caused many merchants not to be able to view
uploaded product images, depending on hosting provider configuration.
Technical Details After Digging Into The Patch
 has been properly replaced with
Mage_Adminhtml_Helper_Sales to fix the PHP < 5.4 backward incompatibility
_makeEventsLowerCase function of
Mage_Core_Model_Config now accepts any
Varien_Simplexml_Config as second parameter instead of
Mage_Core_Model_Config_Base to fix the 500 SOAP API issue.
Varien_File_Uploader permissions have been rolled back to 666 for files (640 with patch V1) and 777 for folders (750 with patch V1) to fix the file upload issues.
- Even if changes have been made to
app/code/core/Mage/Sales/Model/Quote/Item.php to fix the quote items not merged correctly bug it seems like it does not fully address the issue. Fabian Schmengler made the following comment about it:
It still does not fix the issue properly. The problem is, the
buyRequest option is compared when checking for equality. Changed
session => item treated as different. Remaining problem:
related_products is an empty array for products added via product page
and not present when added via list. Also, any arbitrary user POST
data is in the
buyRequest option, so you can actively prevent merging.
&& !$item->getProduct()->hasCustomOptions() from the
compare() method worked great for me so far.
List of files affected
- Patch v1.1 does not contain the changes of Patch v1.0. You need to apply the v1.0 before v1.1.
- Do not forget to rollback the custom changes you made after the v1.0 patch before applying patch v1.1
- Magento 126.96.36.199 includes a modification that is not included in the patch: adds CURLOPT_SSLVERSION as an allowed parameter in Varien_Http_Adapter_Curl