Temporary 'fix' for static block caching issue in Magento 1.9.3.8 (app/code/local/Mage/Cms/Block/Block.php)

Block.php

<?php
/**
 * ***************ATTENTION***************************************
 * This is the temporary fix for the Magento 1.9.3.8 bug
 * See http://magento.stackexchange.com/q/73685/3112?stw=2
 * The only change from app/code/core/Mage/Cms/Block/Block.php
 * is that the getCacheKeyInfo() function below is changed, I 
 * concatenated a string that contains the page url and the block id 
 * In this way the result will be unique each time.
 * ****************************************************************
 *
 * Magento
 *
 * NOTICE OF LICENSE
 *
 * This source file is subject to the Open Software License (OSL 3.0)
 * that is bundled with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://opensource.org/licenses/osl-3.0.php
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@magento.com so we can send you a copy immediately.
 *
 * DISCLAIMER
 *
 * Do not edit or add to this file if you wish to upgrade Magento to newer
 * versions in the future. If you wish to customize Magento for your
 * needs please refer to http://www.magento.com for more information.
 *
 * @category    Mage
 * @package     Mage_Cms
 * @copyright  Copyright (c) 2006-2018 Magento, Inc. (http://www.magento.com)
 * @license    http://opensource.org/licenses/osl-3.0.php  Open Software License (OSL 3.0)
 */


/**
 * Cms block content block
 *
 * @category   Mage
 * @package    Mage_Cms
 * @author     Magento Core Team <core@magentocommerce.com>
 */
class Mage_Cms_Block_Block extends Mage_Core_Block_Abstract
{

    /**
     * Initialize cache
     *
     * @return null
     */
    protected function _construct()
    {
        /*
        * setting cache to save the cms block
        */
        $this->setCacheTags(array(Mage_Cms_Model_Block::CACHE_TAG));
        $this->setCacheLifetime(false);
    }

    /**
     * Prepare Content HTML
     *
     * @return string
     */
    protected function _toHtml()
    {
        $blockId = $this->getBlockId();
        $html = '';
        if ($blockId) {
            $block = Mage::getModel('cms/block')
                ->setStoreId(Mage::app()->getStore()->getId())
                ->load($blockId);
            if ($block->getIsActive()) {
                /* @var $helper Mage_Cms_Helper_Data */
                $helper = Mage::helper('cms');
                $processor = $helper->getBlockTemplateProcessor();
                $html = $processor->filter($block->getContent());
                $this->addModelTags($block);
            }
        }
        return $html;
    }
    
    /**
     * Generates a string based on the page url (for example category/product pages) and concatenate the block id to the url
     * Removes the caracters: /, . , &, = and , from this string
     */
    private function generateUrlBasedString($blockId = null)
    {
        $currentUrl = Mage::helper('core/url')->getCurrentUrl();
        $url = Mage::getSingleton('core/url')->parseUrl($currentUrl);
        $path = '_' . $url->getPath();
        
        $path = str_replace('/', '', $path);
        $path = str_replace('.', '', $path);
        $path = str_replace('&', '', $path);
        $path = str_replace(',', '', $path);
        $path = str_replace('=', '', $path);
        
        if(isset($blockId)) {
            $path .= '_' . $blockId;
        }
        
        return $path;
    }

    /**
     * Retrieve values of properties that unambiguously identify unique content
     *
     * @return array
     */
    public function getCacheKeyInfo()
    {
        $blockId = $this->getBlockId();
        if ($blockId) {
            $result = array(
                'CMS_BLOCK',
                $blockId,
                Mage::app()->getStore()->getCode() . $this->generateUrlBasedString($blockId),
            );
        } else {
            $result = parent::getCacheKeyInfo();
        }
        return $result;
    }
}

Thank you for this - your solution is the only one that works for this for my subcategory listing on latest Magento 1.9.4.1.