SPIGOT-3945: Remove RepairCost tag when cost is 0

nms-patches/ItemStack.patch

@@ -303,7 +303,22 @@
  
          itemstack.d(this.D());
          if (this.tag != null) {
-@@ -513,6 +719,12 @@
+@@ -464,6 +670,14 @@
+     }
+ 
+     public void setRepairCost(int i) {
++        // CraftBukkit start - remove RepairCost tag when 0 (SPIGOT-3945)
++        if (i == 0) {
++            if (this.hasTag()) {
++                this.tag.remove("RepairCost");
++            }
++            return;
++        }
++        // CraftBukkit end
+         if (!this.hasTag()) {
+             this.tag = new NBTTagCompound();
+         }
+@@ -513,6 +727,12 @@
          nbttaglist.add(nbttagcompound);
      }