Before we seriously step into Magento 2 era, please allow me to dissect one more Magento 1 bug. Couple of weeks ago we enabled compilation at one of our client's Magento EE installation as a part of holiday traffic preparations. Goal was to take advantage of performance boost provided by avoiding Magento autoloader through compiling all the Magento classes into several bulky PHP files. Unfortunately things didn't go to plan and we had to disable compilation couple of days later, due to bug in the way catalog product view controller handles 404 forwarding when product exists, but for some reason it isn't viewable (out of stock, disabled, etc.).