Program: 1341
Project: 1341
Buggy source:
public void calcSunlight(){
  for (int x=0; x < (int)chunkDimensions.x; x++) {
    for (int z=0; z < (int)chunkDimensions.z; z++) {
      boolean covered=false;
      for (int y=(int)chunkDimensions.y - 1; y >= 0; y--) {
        if (blocks[x][y][z] == 0 && !covered) {
          float dimming=0.0f;
          dimming+=(parent.getBlock(new Vector3f(getBlockWorldPos(new Vector3f(x + 1,y,z)))) > 0) ? DIMMING_INTENS : 0.0f;
          dimming+=(parent.getBlock(new Vector3f(getBlockWorldPos(new Vector3f(x - 1,y,z)))) > 0) ? DIMMING_INTENS : 0.0f;
          dimming+=(parent.getBlock(new Vector3f(getBlockWorldPos(new Vector3f(x,y,z + 1)))) > 0) ? DIMMING_INTENS : 0.0f;
          dimming+=(parent.getBlock(new Vector3f(getBlockWorldPos(new Vector3f(x,y,z - 1)))) > 0) ? DIMMING_INTENS : 0.0f;
          dimming+=(parent.getBlock(new Vector3f(getBlockWorldPos(new Vector3f(x + 1,y,z + 1)))) > 0) ? DIMMING_INTENS : 0.0f;
          dimming+=(parent.getBlock(new Vector3f(getBlockWorldPos(new Vector3f(x - 1,y,z - 1)))) > 0) ? DIMMING_INTENS : 0.0f;
          dimming+=(parent.getBlock(new Vector3f(getBlockWorldPos(new Vector3f(x + 1,y,z - 1)))) > 0) ? DIMMING_INTENS : 0.0f;
          dimming+=(parent.getBlock(new Vector3f(getBlockWorldPos(new Vector3f(x - 1,y,z + 1)))) > 0) ? DIMMING_INTENS : 0.0f;
          setLight(x,y,z,1.0f - dimming);
        }
 else         if (blocks[x][y][z] == 0 && covered) {
          float luminance=getLight(x - 1,y,z) * LUMINANCE_INTENS;
          luminance+=getLight(x + 1,y,z) * LUMINANCE_INTENS;
          luminance+=getLight(x,y,z + 1) * LUMINANCE_INTENS;
          luminance+=getLight(x,y,z - 1) * LUMINANCE_INTENS;
          luminance+=getLight(x + 1,y,z + 1) * LUMINANCE_INTENS;
          luminance+=getLight(x - 1,y,z - 1) * LUMINANCE_INTENS;
          luminance+=getLight(x + 1,y,z + 1) * LUMINANCE_INTENS;
          luminance+=getLight(x + 1,y,z - 1) * LUMINANCE_INTENS;
          setLight(x,y,z,0.05f + (float)Math.min(luminance,1.0f));
        }
 else {
          covered=true;
        }
      }
    }
  }
}

Fixed version (ground truth):
public void calcSunlight(){
  for (int x=0; x < (int)chunkDimensions.x; x++) {
    for (int z=0; z < (int)chunkDimensions.z; z++) {
      boolean covered=false;
      for (int y=(int)chunkDimensions.y - 1; y >= 0; y--) {
        if (blocks[x][y][z] == 0 && !covered) {
          float dimming=0.0f;
          dimming+=(parent.getBlock(new Vector3f(getBlockWorldPos(new Vector3f(x + 1,y,z)))) > 0) ? DIMMING_INTENS : 0.0f;
          dimming+=(parent.getBlock(new Vector3f(getBlockWorldPos(new Vector3f(x - 1,y,z)))) > 0) ? DIMMING_INTENS : 0.0f;
          dimming+=(parent.getBlock(new Vector3f(getBlockWorldPos(new Vector3f(x,y,z + 1)))) > 0) ? DIMMING_INTENS : 0.0f;
          dimming+=(parent.getBlock(new Vector3f(getBlockWorldPos(new Vector3f(x,y,z - 1)))) > 0) ? DIMMING_INTENS : 0.0f;
          dimming+=(parent.getBlock(new Vector3f(getBlockWorldPos(new Vector3f(x + 1,y,z + 1)))) > 0) ? DIMMING_INTENS : 0.0f;
          dimming+=(parent.getBlock(new Vector3f(getBlockWorldPos(new Vector3f(x - 1,y,z - 1)))) > 0) ? DIMMING_INTENS : 0.0f;
          dimming+=(parent.getBlock(new Vector3f(getBlockWorldPos(new Vector3f(x + 1,y,z - 1)))) > 0) ? DIMMING_INTENS : 0.0f;
          dimming+=(parent.getBlock(new Vector3f(getBlockWorldPos(new Vector3f(x - 1,y,z + 1)))) > 0) ? DIMMING_INTENS : 0.0f;
          setLight(x,y,z,1.0f - dimming);
        }
 else         if (blocks[x][y][z] == 0 && covered) {
          float luminance=getLight(x - 1,y,z) * LUMINANCE_INTENS;
          luminance+=getLight(x + 1,y,z) * LUMINANCE_INTENS;
          luminance+=getLight(x,y,z + 1) * LUMINANCE_INTENS;
          luminance+=getLight(x,y,z - 1) * LUMINANCE_INTENS;
          luminance+=getLight(x + 1,y,z + 1) * LUMINANCE_INTENS;
          luminance+=getLight(x - 1,y,z - 1) * LUMINANCE_INTENS;
          luminance+=getLight(x + 1,y,z + 1) * LUMINANCE_INTENS;
          luminance+=getLight(x + 1,y,z - 1) * LUMINANCE_INTENS;
          setLight(x,y,z,0.1f + (float)Math.min(luminance,1.0f));
        }
 else {
          covered=true;
        }
      }
    }
  }
}