Program: 10641
Project: 10641
Buggy source:
@Override public void renderTileEntityAt(TileEntity tile,double x,double y,double z,float partialTickTime){
  TileEntityDrawers tileDrawers=(TileEntityDrawers)tile;
  if (tileDrawers == null)   return;
  GL11.glPushMatrix();
  GL11.glTranslated(x,y,z);
  int drawerCount=tileDrawers.getDrawerCount();
  float depth=1;
  float unit=.0625f;
  Block block=tile.getWorldObj().getBlock(tile.xCoord,tile.yCoord,tile.zCoord);
  if (block instanceof BlockDrawers)   depth=((BlockDrawers)block).halfDepth ? .5f : 1;
 else   return;
  itemRenderer.setRenderManager(RenderManager.instance);
  for (int i=0; i < drawerCount; i++) {
    ItemStack itemStack=tileDrawers.getSingleItemStack(i);
    if (itemStack != null) {
      GL11.glPushMatrix();
      boolean blockType=itemStack.getItemSpriteNumber() == 0 && itemStack.getItem() instanceof ItemBlock && RenderBlocks.renderItemIn3d(Block.getBlockFromItem(itemStack.getItem()).getRenderType());
      float xunit=(drawerCount == 2) ? itemOffset2X[i] : itemOffset4X[i];
      float yunit=(drawerCount == 2) ? itemOffset2Y[i] : itemOffset4Y[i];
      float zunit=blockType ? 1.95f * unit : unit;
      float xc=0, zc=0;
      float itemDepth=depth + .001f;
      if (blockType) {
        Block itemBlock=Block.getBlockFromItem(itemStack.getItem());
        itemBlock.setBlockBoundsForItemRender();
        double zDepth=1 - itemBlock.getBlockBoundsMaxZ();
        itemDepth+=zDepth * zunit;
      }
switch (tileDrawers.getDirection()) {
case 3:
        xc=xunit;
      zc=itemDepth - zunit;
    break;
case 2:
  xc=1 - xunit;
zc=1 - itemDepth + zunit;
break;
case 5:
xc=itemDepth - zunit;
zc=xunit;
break;
case 4:
xc=1 - itemDepth + zunit;
zc=1 - xunit;
break;
}
Minecraft mc=Minecraft.getMinecraft();
boolean cache=mc.gameSettings.fancyGraphics;
mc.gameSettings.fancyGraphics=true;
ForgeDirection side=ForgeDirection.getOrientation(tileDrawers.getDirection());
if (StorageDrawers.config.isFancyItemRenderEnabled()) {
if (blockType) {
GL11.glTranslatef(xc,unit * (yunit + 1.25f),zc);
GL11.glScalef(1,1,1);
GL11.glRotatef(getRotationYForSide(side,side) - 90.0F,0.0F,1.0F,0.0F);
}
 else {
GL11.glTranslatef(xc,unit * yunit,zc);
GL11.glScalef(.6f,.6f,.6f);
GL11.glRotatef(getRotationYForSide(side,side),0.0F,1.0F,0.0F);
}
EntityItem itemEnt=new EntityItem(null,0,0,0,itemStack);
itemEnt.hoverStart=0;
itemRenderer.doRender(itemEnt,0,0,0,0,0);
}
 else {
alignRendering(side,side);
moveRendering(.25f,xunit * 16 - 2,yunit,.999f - depth + unit);
itemRenderer.renderItemAndEffectIntoGUI(mc.fontRenderer,mc.renderEngine,itemStack,0,0);
}
mc.gameSettings.fancyGraphics=cache;
GL11.glPopMatrix();
}
}
GL11.glPopMatrix();
}

Fixed version (ground truth):
@Override public void renderTileEntityAt(TileEntity tile,double x,double y,double z,float partialTickTime){
  TileEntityDrawers tileDrawers=(TileEntityDrawers)tile;
  if (tileDrawers == null)   return;
  saveGLState();
  GL11.glPushMatrix();
  GL11.glTranslated(x,y,z);
  int drawerCount=tileDrawers.getDrawerCount();
  float depth=1;
  float unit=.0625f;
  Block block=tile.getWorldObj().getBlock(tile.xCoord,tile.yCoord,tile.zCoord);
  if (block instanceof BlockDrawers)   depth=((BlockDrawers)block).halfDepth ? .5f : 1;
 else   return;
  itemRenderer.setRenderManager(RenderManager.instance);
  ForgeDirection side=ForgeDirection.getOrientation(tileDrawers.getDirection());
  int ambLight=tile.getWorldObj().getLightBrightnessForSkyBlocks(tile.xCoord + side.offsetX,tile.yCoord + side.offsetY,tile.zCoord + side.offsetZ,0);
  int lu=ambLight % 65536;
  int lv=ambLight / 65536;
  OpenGlHelper.setLightmapTextureCoords(OpenGlHelper.lightmapTexUnit,lu,lv);
  for (int i=0; i < drawerCount; i++) {
    GL11.glDisable(GL11.GL_BLEND);
    GL11.glDisable(GL11.GL_LIGHTING);
    ItemStack itemStack=tileDrawers.getSingleItemStack(i);
    if (itemStack != null) {
      GL11.glPushMatrix();
      boolean blockType=itemStack.getItemSpriteNumber() == 0 && itemStack.getItem() instanceof ItemBlock && RenderBlocks.renderItemIn3d(Block.getBlockFromItem(itemStack.getItem()).getRenderType());
      float xunit=(drawerCount == 2) ? itemOffset2X[i] : itemOffset4X[i];
      float yunit=(drawerCount == 2) ? itemOffset2Y[i] : itemOffset4Y[i];
      float zunit=blockType ? 1.95f * unit : unit;
      float xc=0, zc=0;
      float itemDepth=depth + .001f;
      if (blockType) {
        Block itemBlock=Block.getBlockFromItem(itemStack.getItem());
        itemBlock.setBlockBoundsForItemRender();
        double zDepth=1 - itemBlock.getBlockBoundsMaxZ();
        itemDepth+=zDepth * zunit;
      }
switch (tileDrawers.getDirection()) {
case 3:
        xc=xunit;
      zc=itemDepth - zunit;
    break;
case 2:
  xc=1 - xunit;
zc=1 - itemDepth + zunit;
break;
case 5:
xc=itemDepth - zunit;
zc=xunit;
break;
case 4:
xc=1 - itemDepth + zunit;
zc=1 - xunit;
break;
}
Minecraft mc=Minecraft.getMinecraft();
boolean cache=mc.gameSettings.fancyGraphics;
mc.gameSettings.fancyGraphics=true;
if (StorageDrawers.config.isFancyItemRenderEnabled()) {
if (blockType) {
GL11.glTranslatef(xc,unit * (yunit + 1.25f),zc);
GL11.glScalef(1,1,1);
GL11.glRotatef(getRotationYForSide(side) - 90.0F,0.0F,1.0F,0.0F);
}
 else {
GL11.glTranslatef(xc,unit * yunit,zc);
GL11.glScalef(.6f,.6f,.6f);
GL11.glRotatef(getRotationYForSide(side),0.0F,1.0F,0.0F);
}
EntityItem itemEnt=new EntityItem(null,0,0,0,itemStack);
itemEnt.hoverStart=0;
itemRenderer.doRender(itemEnt,0,0,0,0,0);
}
 else {
alignRendering(side);
moveRendering(.25f,getOffsetXForSide(side,xunit) * 16 - 2,12.5f - yunit,.999f - depth + unit);
if (!ForgeHooksClient.renderInventoryItem(this.renderBlocks,mc.renderEngine,itemStack,true,0,0,0)) itemRenderer.renderItemIntoGUI(mc.fontRenderer,mc.renderEngine,itemStack,0,0,true);
}
mc.gameSettings.fancyGraphics=cache;
GL11.glPopMatrix();
}
}
GL11.glPopMatrix();
loadGLState();
}