Set current recipe to null when a recipe isn't found. Fixes BUKKIT-2311

This commit restores the diff from 84dbc21aa71b96fd1d2ea40d624b536309118cde
that has since been lost.

src/main/java/net/minecraft/server/CraftingManager.java

@@ -295,6 +295,7 @@ public class CraftingManager {
                 }
             }
 
+            inventorycrafting.currentRecipe = null; // CraftBukkit - Clear recipe when no recipe is found
             return null;
         }
     }