Fix fluid tanks incorrectly reading NBT when empty

If the Empty flag was set, the tank would not correctly read the data, keeping the outdated FluidStack instead. This is especially relevant with updatable TileFluidHandler TEs.

src/main/java/net/minecraftforge/fluids/FluidTank.java

@@ -37,11 +37,11 @@ public class FluidTank implements IFluidTank
         if (!nbt.hasKey("Empty"))
         {
             FluidStack fluid = FluidStack.loadFluidStackFromNBT(nbt);
-
-            if (fluid != null)
-            {
-                setFluid(fluid);
-            }
+            setFluid(fluid);
+        }
+        else
+        {
+            setFluid(null);
         }
         return this;
     }