Program: 156527
Project: 156527
Buggy source:
@Override public void useRequirements(IInventory inv,BuildingSlot slot){
  if (slot instanceof BuildingSlotBlock && ((BuildingSlotBlock)slot).mode == Mode.ClearIfInvalid) {
    return;
  }
  LinkedList<ItemStack> tmpReq=new LinkedList<ItemStack>();
  try {
    for (    ItemStack stk : slot.getRequirements(context)) {
      if (stk != null) {
        tmpReq.add(stk.copy());
      }
    }
  }
 catch (  Throwable t) {
    t.printStackTrace();
    BCLog.logger.throwing(t);
  }
  if (context.world().getWorldInfo().getGameType() == GameType.CREATIVE) {
    for (    ItemStack s : tmpReq) {
      slot.addStackConsumed(s);
    }
    return;
  }
  ListIterator<ItemStack> itr=tmpReq.listIterator();
  while (itr.hasNext()) {
    ItemStack reqStk=itr.next();
    boolean smallStack=reqStk.stackSize == 1;
    ItemStack usedStack=reqStk;
    boolean itemBlock=reqStk.getItem() instanceof ItemBlock;
    Fluid fluid=itemBlock ? FluidRegistry.lookupFluidForBlock(((ItemBlock)reqStk.getItem()).field_150939_a) : null;
    if (fluid != null && inv instanceof TileAbstractBuilder && ((TileAbstractBuilder)inv).drainBuild(new FluidStack(fluid,FluidContainerRegistry.BUCKET_VOLUME),true)) {
      continue;
    }
    for (    IInvSlot slotInv : InventoryIterator.getIterable(inv,ForgeDirection.UNKNOWN)) {
      if (inv instanceof TileAbstractBuilder && !((TileAbstractBuilder)inv).isBuildingMaterialSlot(slotInv.getIndex())) {
        continue;
      }
      ItemStack invStk=slotInv.getStackInSlot();
      if (invStk == null || invStk.stackSize == 0) {
        continue;
      }
      FluidStack fluidStack=fluid != null ? FluidContainerRegistry.getFluidForFilledItem(invStk) : null;
      boolean fluidFound=fluidStack != null && fluidStack.getFluid() == fluid && fluidStack.amount >= FluidContainerRegistry.BUCKET_VOLUME;
      if (fluidFound || StackHelper.isEqualItem(reqStk,invStk)) {
        try {
          usedStack=slot.getSchematic().useItem(context,reqStk,slotInv);
          slot.addStackConsumed(usedStack);
        }
 catch (        Throwable t) {
          t.printStackTrace();
          BCLog.logger.throwing(t);
        }
        if (reqStk.stackSize == 0) {
          break;
        }
      }
    }
    if (reqStk.stackSize != 0) {
      return;
    }
    if (smallStack) {
      itr.set(usedStack);
    }
  }
}

Fixed version (ground truth):
@Override public void useRequirements(IInventory inv,BuildingSlot slot){
  if (slot instanceof BuildingSlotBlock && ((BuildingSlotBlock)slot).mode == Mode.ClearIfInvalid) {
    return;
  }
  LinkedList<ItemStack> tmpReq=new LinkedList<ItemStack>();
  try {
    for (    ItemStack stk : slot.getRequirements(context)) {
      if (stk != null) {
        tmpReq.add(stk.copy());
      }
    }
  }
 catch (  Throwable t) {
    t.printStackTrace();
    BCLog.logger.throwing(t);
  }
  if (context.world().getWorldInfo().getGameType() == GameType.CREATIVE) {
    for (    ItemStack s : tmpReq) {
      slot.addStackConsumed(s);
    }
    return;
  }
  ListIterator<ItemStack> itr=tmpReq.listIterator();
  while (itr.hasNext()) {
    ItemStack reqStk=itr.next();
    boolean smallStack=reqStk.stackSize == 1;
    ItemStack usedStack=reqStk;
    boolean itemBlock=reqStk.getItem() instanceof ItemBlock;
    Fluid fluid=itemBlock ? FluidRegistry.lookupFluidForBlock(((ItemBlock)reqStk.getItem()).field_150939_a) : null;
    if (fluid != null && inv instanceof TileAbstractBuilder && ((TileAbstractBuilder)inv).drainBuild(new FluidStack(fluid,FluidContainerRegistry.BUCKET_VOLUME),true)) {
      continue;
    }
    for (    IInvSlot slotInv : InventoryIterator.getIterable(inv,ForgeDirection.UNKNOWN)) {
      if (inv instanceof TileAbstractBuilder && !((TileAbstractBuilder)inv).isBuildingMaterialSlot(slotInv.getIndex())) {
        continue;
      }
      ItemStack invStk=slotInv.getStackInSlot();
      if (invStk == null || invStk.stackSize == 0) {
        continue;
      }
      FluidStack fluidStack=fluid != null ? FluidContainerRegistry.getFluidForFilledItem(invStk) : null;
      boolean fluidFound=fluidStack != null && fluidStack.getFluid() == fluid && fluidStack.amount >= FluidContainerRegistry.BUCKET_VOLUME;
      if (fluidFound || slot.getSchematic().isItemMatchingRequirement(invStk,reqStk)) {
        try {
          usedStack=slot.getSchematic().useItem(context,reqStk,slotInv);
          slot.addStackConsumed(usedStack);
        }
 catch (        Throwable t) {
          t.printStackTrace();
          BCLog.logger.throwing(t);
        }
        if (reqStk.stackSize == 0) {
          break;
        }
      }
    }
    if (reqStk.stackSize != 0) {
      return;
    }
    if (smallStack) {
      itr.set(usedStack);
    }
  }
}