Program: 169518
Project: 169518
Buggy source:
private boolean matchAndProcessColumn(IInventory inputInventory,int[] accessibleSlots,int column){
  List<ItemStack> requirements=new ArrayList<ItemStack>();
  for (int i=0; i < 5; i++) {
    ItemStack filterStack=inventory[column + 8 * i];
    if (filterStack != null) {
      boolean duplicate=false;
      for (      ItemStack requirement : requirements) {
        if (WidgetFuzzySetting.areStacksEqual(requirement,filterStack,fuzzySettings[column])) {
          requirement.stackSize+=filterStack.stackSize;
          duplicate=true;
          break;
        }
      }
      if (!duplicate)       requirements.add(filterStack.copy());
    }
  }
  if (requirements.size() == 0)   return false;
  ItemStack[] copy=new ItemStack[requirements.size()];
  for (int i=0; i < copy.length; i++)   copy[i]=requirements.get(i).copy();
  Iterator<ItemStack> iterator=requirements.iterator();
  while (iterator.hasNext()) {
    ItemStack stack=iterator.next();
    for (    int slot : accessibleSlots) {
      ItemStack invStack=inputInventory.getStackInSlot(slot);
      if (invStack != null && WidgetFuzzySetting.areStacksEqual(invStack,stack,fuzzySettings[column])) {
        stack.stackSize-=invStack.stackSize;
        if (stack.stackSize <= 0) {
          iterator.remove();
          break;
        }
      }
    }
  }
  if (requirements.isEmpty()) {
    for (    ItemStack stack : copy) {
      for (      int slot : accessibleSlots) {
        if (stack.stackSize > 0) {
          ItemStack invStack=inputInventory.getStackInSlot(slot);
          if (invStack != null && WidgetFuzzySetting.areStacksEqual(invStack,stack,fuzzySettings[column])) {
            int substracted=Math.min(stack.stackSize,invStack.stackSize);
            stack.stackSize-=substracted;
            invStack.stackSize-=substracted;
            if (invStack.stackSize <= 0) {
              inputInventory.setInventorySlotContents(slot,null);
            }
            ItemStack bufferStack=invStack.copy();
            bufferStack.stackSize=substracted;
            addItemToOutputBuffer(bufferStack,colors[column]);
          }
        }
      }
    }
    inputInventory.markDirty();
    return true;
  }
 else {
    return false;
  }
}

Fixed version (ground truth):
private boolean matchAndProcessColumn(IInventory inputInventory,int[] accessibleSlots,int column){
  List<ItemStack> requirements=new ArrayList<ItemStack>();
  for (int i=0; i < 5; i++) {
    ItemStack filterStack=inventory[column + 8 * i];
    if (filterStack != null) {
      boolean duplicate=false;
      for (      ItemStack requirement : requirements) {
        if (ItemStackHelper.areStacksEqual(requirement,filterStack,fuzzySettings[column])) {
          requirement.stackSize+=filterStack.stackSize;
          duplicate=true;
          break;
        }
      }
      if (!duplicate)       requirements.add(filterStack.copy());
    }
  }
  if (requirements.size() == 0)   return false;
  ItemStack[] copy=new ItemStack[requirements.size()];
  for (int i=0; i < copy.length; i++)   copy[i]=requirements.get(i).copy();
  Iterator<ItemStack> iterator=requirements.iterator();
  while (iterator.hasNext()) {
    ItemStack stack=iterator.next();
    for (    int slot : accessibleSlots) {
      ItemStack invStack=inputInventory.getStackInSlot(slot);
      if (invStack != null && ItemStackHelper.areStacksEqual(invStack,stack,fuzzySettings[column])) {
        stack.stackSize-=invStack.stackSize;
        if (stack.stackSize <= 0) {
          iterator.remove();
          break;
        }
      }
    }
  }
  if (requirements.isEmpty()) {
    for (    ItemStack stack : copy) {
      for (      int slot : accessibleSlots) {
        if (stack.stackSize > 0) {
          ItemStack invStack=inputInventory.getStackInSlot(slot);
          if (invStack != null && ItemStackHelper.areStacksEqual(invStack,stack,fuzzySettings[column])) {
            int substracted=Math.min(stack.stackSize,invStack.stackSize);
            stack.stackSize-=substracted;
            invStack.stackSize-=substracted;
            if (invStack.stackSize <= 0) {
              inputInventory.setInventorySlotContents(slot,null);
            }
            ItemStack bufferStack=invStack.copy();
            bufferStack.stackSize=substracted;
            addItemToOutputBuffer(bufferStack,colors[column]);
          }
        }
      }
    }
    inputInventory.markDirty();
    return true;
  }
 else {
    return false;
  }
}