Kalista Rend Bug

So with the patch it might have been fixed but I didn't see anything about it so I'd figure I would post this anyways. You can cast Rend even if you do not have the mana to cast it, it still consumes your mana but it is castable if you have less than 40 mana. The screenshot shows that I have less than 40 mana, a creep has a spear stuck in it and Rend isn't blued out as not enough mana.