Implemented When did this take effect?

I was flying through the nether and I knew I had fire res on so I went ahead and fell toward the lava but instead it saids I fell to my death? Losing all my items in the lava...I thought the lava was supposed to act as fluid were you can pretty much swim in it...

 

sometimes lava bugs out on servers fora few reasons and causes you to take fall damage (yes even in vanilla)

 

So is it possible I can get my items that I lost due to a bug then?

 

Ok, will keep that in mind then.