Program: 149475
Project: 149475
Buggy source:
public void renderBlock(IBlockRenderer par1,BlockStack par2,RenderBlocks par3){
  float[] size=par1.getBoundingBoxes(par2.getMeta());
  if (size == null || size.length < 6) {
    size=new float[]{0,0,0,1,1,1};
  }
  Icon[] textureArray=new Icon[6];
  for (int i=0; i < 6; i++) {
    Icon blockIcon=par2.getTexture(i);
    if (blockIcon == null || !engine.isTextureRegistered(blockIcon,engine.getTextureMap())) {
      blockIcon=engine.getIconSafe();
    }
    textureArray[i]=blockIcon;
  }
  Tessellator tessellator=Tessellator.instance;
  Block block=par2.getBlock();
  block.setBlockBounds(size[0],size[1],size[2],size[3],size[4],size[5]);
  block.setBlockBoundsForItemRender();
  par3.setRenderBoundsFromBlock(block);
  GL11.glTranslatef(-0.5F,-0.5F,-0.5F);
  tessellator.startDrawingQuads();
  tessellator.setNormal(0.0F,-1.0F,0.0F);
  par3.renderFaceYNeg(block,0.0D,0.0D,0.0D,textureArray[0]);
  tessellator.draw();
  tessellator.startDrawingQuads();
  tessellator.setNormal(0.0F,1.0F,0.0F);
  par3.renderFaceYPos(block,0.0D,0.0D,0.0D,textureArray[0]);
  tessellator.draw();
  tessellator.startDrawingQuads();
  tessellator.setNormal(0.0F,0.0F,-1.0F);
  par3.renderFaceZNeg(block,0.0D,0.0D,0.0D,textureArray[0]);
  tessellator.draw();
  tessellator.startDrawingQuads();
  tessellator.setNormal(0.0F,0.0F,1.0F);
  par3.renderFaceZPos(block,0.0D,0.0D,0.0D,textureArray[0]);
  tessellator.draw();
  tessellator.startDrawingQuads();
  tessellator.setNormal(-1.0F,0.0F,0.0F);
  par3.renderFaceXNeg(block,0.0D,0.0D,0.0D,textureArray[0]);
  tessellator.draw();
  tessellator.startDrawingQuads();
  tessellator.setNormal(1.0F,0.0F,0.0F);
  par3.renderFaceXPos(block,0.0D,0.0D,0.0D,textureArray[0]);
  tessellator.draw();
  GL11.glTranslatef(0.5F,0.5F,0.5F);
  block.setBlockBounds(0.0F,0.0F,0.0F,1.0F,1.0F,1.0F);
}

Fixed version (ground truth):
public void renderBlock(IBlockRenderer par1,BlockStack par2,RenderBlocks par3,ItemRenderType par4){
  float[] size=par1.getBoundingBoxes(par2.getMeta());
  if (size == null || size.length < 6) {
    size=new float[]{0,0,0,1,1,1};
  }
  Icon[] textureArray=new Icon[6];
  for (int i=0; i < 6; i++) {
    Icon blockIcon=par2.getTexture(i);
    if (blockIcon == null || !engine.isTextureRegistered(blockIcon,engine.getTextureMap())) {
      blockIcon=engine.getIconSafe();
    }
    textureArray[i]=blockIcon;
  }
  float[] data=par1.getXYZForItemRenderer(par4,par2.getMeta());
  if (data == null || data.length != 3) {
    data=new float[]{-0.5F,-0.5F,-0.5F};
  }
  Tessellator tessellator=Tessellator.instance;
  Block block=par2.getBlock();
  block.setBlockBounds(size[0],size[1],size[2],size[3],size[4],size[5]);
  block.setBlockBoundsForItemRender();
  par3.setRenderBoundsFromBlock(block);
  GL11.glTranslatef(data[0],data[1],data[2]);
  tessellator.startDrawingQuads();
  tessellator.setNormal(0.0F,-1.0F,0.0F);
  par3.renderFaceYNeg(block,0.0D,0.0D,0.0D,textureArray[0]);
  tessellator.draw();
  tessellator.startDrawingQuads();
  tessellator.setNormal(0.0F,1.0F,0.0F);
  par3.renderFaceYPos(block,0.0D,0.0D,0.0D,textureArray[0]);
  tessellator.draw();
  tessellator.startDrawingQuads();
  tessellator.setNormal(0.0F,0.0F,-1.0F);
  par3.renderFaceZNeg(block,0.0D,0.0D,0.0D,textureArray[0]);
  tessellator.draw();
  tessellator.startDrawingQuads();
  tessellator.setNormal(0.0F,0.0F,1.0F);
  par3.renderFaceZPos(block,0.0D,0.0D,0.0D,textureArray[0]);
  tessellator.draw();
  tessellator.startDrawingQuads();
  tessellator.setNormal(-1.0F,0.0F,0.0F);
  par3.renderFaceXNeg(block,0.0D,0.0D,0.0D,textureArray[0]);
  tessellator.draw();
  tessellator.startDrawingQuads();
  tessellator.setNormal(1.0F,0.0F,0.0F);
  par3.renderFaceXPos(block,0.0D,0.0D,0.0D,textureArray[0]);
  tessellator.draw();
  GL11.glTranslatef(0.5F,0.5F,0.5F);
  block.setBlockBounds(0.0F,0.0F,0.0F,1.0F,1.0F,1.0F);
}