We had to remove sanity check [here](https://github.com/CartoDB/Windshaft/commit/d3938287bdf859ac83ba8c4e62bc713217d96a92). As long as things are getting stable on prod, we should get it back. Furthermore we need to improve this [test](https://github.com/CartoDB/Windshaft/blob/master/test/acceptance/multilayer.js#L488-L496) to check that layergroupid didn't change when mapconfig uses 'utf-8' special characters.
