Python script to fix Minecraft 14w26a/b snapshots. Needs https://github.com/mcedit/pymclevel to run

fix_chunks.py

#!/usr/bin/env python
import os
import sys

if __name__ == "__main__":
    # Unbuffer stdout
    sys.stdout = os.fdopen(sys.stdout.fileno(), 'w', 0)

    print "Loading world...",
    from pymclevel import mclevel
    level = mclevel.fromFile(sys.argv[1])
    print "done."
    for dim in level.dimensions.values() + [level]:
        chunkCoords = list(dim.allChunks)
        i = 0
        total = len(chunkCoords)
        fc = "Fixing chunks for %s..." % dim.displayName
        print fc,
        fci = len(fc) + 2
        for coord in chunkCoords:
            chunk = dim.getChunk(*coord)
            if i % 10 == 0: print "\033[%dG%0.2f%%" % (fci, float(i) / total * 100),
            chunk.Blocks[:] = chunk.Blocks[:] & 255
            chunk.chunkChanged(False)
            i += 1
        print "\033[%dG\033[Kdone." % fci
    print "Saving world...",
    level.saveInPlace()
    print "done."
else:
    raise ImportError, "Not meant to be imported"