I was playing on a brand new world searching for an Ice Spikes biome when I saw that. The latest version is dated of today so let's hope it will be fixed soon.
MC-40639
Water do not fall
Resolved
Duplicate
0
Ulroip
(Unassigned)
Unconfirmed
water
Minecraft 13w47e
Retrieved
Its generated terain. Basically the water is generated before the cave/cavern so the water doesn't know its been cut off. When there's block up date it should flow freely