See screenshot "1.7.10" which was taken in Minecraft 1.7.10, and screenshot "14w31a" which was taken in Minecraft 14w31a. Both using "Large Biomes" world type with seed -4253180711807921163, floating at position (107,155,35) looking at the same small lake.

Notice that version 14w31a has significantly more river. I believe this is because the snapshot is using the river placement from "Default" world type, meaning that rivers are not being spread out the same way other biomes are. Note that previous versions of Minecraft used the correct skewed placement (to match the Large Biome theme).

This is an error in world generation because (1) rivers are not being skewed and positioned as they should and (2) because previous versions of Minecraft skewed and positioned them as expected.

For what it's worth: I've used AMDIST to map the seed in both Default and Large Biome versions, and it turns out that the rivers in Minecraft 1431a are indeed being placed in the exact same locations they would if the world were Default type.