there used to be an update to the swamps so they'd look more swampy and thats in 13w37a or earlier snapshots ( intended for the 1.7 biomes/ocean update).
They added little pools to the edge of the swamp landmass and little islands like in a marsh.
But now (in version 13w39b) i load in a seed and the pools are gone, have they removed it or is this a bug?
I seriously hope its a bug but highly doubt it because it still shows the pools in earlier snapshots :S.
I never play in swamps because they were kinda boring, but with those pools they looked very VERY nice! i hope if its an update, they read my report and reintegrate it.
Here are some pics. of the issue before and after. (its in both the same seed and in earlier version it shows the pools and in the latest it doesn't).
hope this gets fixed or reintegrated.