Seems the that after the Server Maintenance and a Micro Patch on the Russian Server, Low Tier Tanks are now able to play maps destined for High Tier. Some players shared some games in Tier 4 Tanks playing maps like Cliff, Lakeville, Erlenberg and Swamp.
*UPDATE*
Seems NA Servers after the micro patch were also affected by this. I believe the micro patch is coming out on EU Servers tomorrow, couldn’t yet confirm this. But lets see what we get.
http://cs7002.vk.me/v7002831/155ac/EhcuBMFxZec.jpg
http://cs7002.vk.me/v7002338/15488/6G20BGG-f9k.jpg
http://cs7002.vk.me/v7002583/15593/awQHu9HKtZ0.jpg
http://cs627722.vk.me/v627722571/345a5/RGlRu3fjK0M.jpg