Check rewrites not fully working

[grossmann]

The rewrite checks seems to not working fully correct.
With just 2 modules installed ( FireGento_GermanSetup and Sitewards_B2BProfessional) they both extend the class Mage_Catalog_Block_Product_Price. But Firegento don't show an error because the files where the class is extended reside in different paths in the file systems.

Core: magento\app\code\core\Mage\Catalog\Block\Product\Price.php
GermanSetup: magento\app\code\community\FireGento\GermanSetup\Block\Catalog\Product\Price.php
B2BProffessional: magento\app\code\community\Sitewards\B2BProfessional\Block\Price.php

I think Firegento should not just check for the path (which can differ very much) but also for the extended classes if there happens a rewrite.