Sometimes Water/Lava flows out of newly generated Village Farms / Forges

happened to me to. I used Superflat though and it was at two villages. Seed:-60146107116314948 X:-1158 Y:14 Z:332 and X:-900 Y:9 Z:338

Added a screenshot of the village I found on a default superflat world I created.

Not just superflat worlds, here's one from largeBiomes. MC Version snapshot 13w24b. Seed 2028444982885494103, x=803, y=74, z=84.

I see this all the time.... also when taking away water sources, sometimes a corner acts as a source block

I started getting this on Superflat worlds after the last Snapshot.

I see tons of duplicate reports, but none of them return to vote. I suspect this issue won;t be touched for months.

I just opened a new world in 1.6.1 and saw this issue.

Is this still a concern in the current Minecraft version? If so, please update the affected versions in order to best aid Mojang ensuring bugs are still valid in the latest releases/pre-releases.

Still in 1.6.2

happens with lava in blacksmith house's too. see images in MC-26697

Probable reason
Going through those few cases where players have bothered to provide seeds, settings and locations, this seems to be a side-effect from the way "decorations" are added to world - shifted by half a chunk. Thus, when farms (or any other structures) are generated and inserted into the world, they can be inserted partially (cut at half-chunk positions), the other part(s) of the structure being inserted later, when player moves and allows generating more chunks. If the cutting happens to be next to a flowing block, there is half a chunk more space to flow into. Later when player moves, the other parts will overwrite some of the flowing water blocks without mercy, leaving the remnants as artifacts reported here.

Note, normal water generation is done per full chunk, and uses "still water" block, instead of "moving water" block. I do not know why, but in changing the village farm water blocks into "still water" type seems to fix the symptoms. Or more like, it is a workaround, since the real reason is the half a block shift (which causes more issues than just this one). Likely, the same could be applied to the "moving lava" used in one house, however, I do not have suitable test case for that.

A proper fix might be to implement some additional code that delays/prevents planting a structure (or a full independent part of a structure, depending on terminology) into the world until all of it can be planted at once, but that is beyond the scope of a comment here. However, this approach can have other nasty issues due to the way how some decorations will then be possibly planted when they shouldn't be, as they won't know about the delayed structure. (That last part is the roughly reason e.g. why lakes sometimes carve tree or building bottoms out; the trees/buildings do not know about the lake coming later...)

Here is example of workarounds, for those who want to test if it really works for them, too:

ComponentVillageField.addComponentParts()

//this.fillWithBlocks(par1World, par3StructureBoundingBox, 3, 0, 1, 3, 0, 7, Block.waterMoving.blockID, Block.waterMoving.blockID, false);
        //this.fillWithBlocks(par1World, par3StructureBoundingBox, 9, 0, 1, 9, 0, 7, Block.waterMoving.blockID, Block.waterMoving.blockID, false);
        this.fillWithBlocks(par1World, par3StructureBoundingBox, 3, 0, 1, 3, 0, 7, Block.waterStill.blockID, Block.waterStill.blockID, false);
        this.fillWithBlocks(par1World, par3StructureBoundingBox, 9, 0, 1, 9, 0, 7, Block.waterStill.blockID, Block.waterStill.blockID, false);

ComponentVillageField2.addComponentParts()

//this.fillWithBlocks(par1World, par3StructureBoundingBox, 3, 0, 1, 3, 0, 7, Block.waterMoving.blockID, Block.waterMoving.blockID, false);
        this.fillWithBlocks(par1World, par3StructureBoundingBox, 3, 0, 1, 3, 0, 7, Block.waterStill.blockID, Block.waterStill.blockID, false);

I had this a few days ago in my 15w49b server, going to provide seed and coords later, as I'm not on my pc now

Edit:
ok, weird, I generated a world with the same seed, got to the same coords, and now it wasn't there

IIRC, this bug was back then a slightly randomly appearing, as it depended in some cases on direction in which the user approached the village from, the exact chunks traveled (thus exact order of chunks generated), or even some timing related issues. Especially, warping directly on the village may fail to show the issue. It is best to teleport just outside the generation range of the village (note, it might not be the same as rendering distance), note which direction the approach is, see if issue happens. Note, even small (one chunk) differences in the approach (and thus chunk generation order) could affect the result.

To search for cases, it is best to just fly around in superflat, instead of regenerating the same world or same village. Only once the issue shows up, record the direction of movement and village location, and try to repeat with the same direction & village.

Happy leak hunting.