If you place sponge in water, it removes the water around it, but doesn't update it, so the water doesn't flow.
What I expected to happen was...:
Sponges remove water and update the blocks around it, like it has always been.
What actually happened was...:
Sponges remove water, but don't update the water blocks, so they don't flow.

Steps to Reproduce:
Place a block of sponge in a pool of water.
Water will get removed, but the water left around the pocket will not update.