What I expected to happen:
Produce Potion of Leaping with an extended duration (8:00).

What actually happened:
Nothing.

Steps to reproduce:
1. Get a brewing stand and put a bottle of water in it.
2. Produce an Awkward Potion using a Nether Wart.
3. Produce a Potion of Leaping using a Rabbit's Foot.
4. Place Redstone in the brewing stand and nothing will happen.

I'm not entirely sure if this is an intended feature, but I'm able to use redstone in a brewing stand to extend any potion's duration except for potions of leaping. I first realized this when I was looking through the brewing section of the creative mode item selection GUI and saw that there was no Potion of Leaping (8:00). I tested to see if I could produce one legitimately, but to no avail.