Fixed losing an infinite item when interacting with an entity. Thanks for the help Rigby!

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

@@ -512,7 +512,8 @@ public abstract class EntityHuman extends EntityLiving {
 
             if (itemstack != null && entity instanceof EntityLiving) {
                 itemstack.a((EntityLiving) entity);
-                if (itemstack.count <= 0) {
+                // CraftBukkit - bypass infinite items; <= 0 -> == 0
+                if (itemstack.count == 0) {
                     itemstack.a(this);
                     this.G();
                 }
@@ -573,7 +574,8 @@ public abstract class EntityHuman extends EntityLiving {
 
             if (itemstack != null && entity instanceof EntityLiving) {
                 itemstack.a((EntityLiving) entity, this);
-                if (itemstack.count <= 0) {
+                // CraftBukkit - bypass infinite items; <= 0 -> == 0
+                if (itemstack.count == 0) {
                     itemstack.a(this);
                     this.G();
                 }

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

@@ -869,8 +869,18 @@ public class NetServerHandler extends NetHandler implements ICommandListener {
                 }
                 // CraftBukkit end
                 this.player.c(entity);
+                // CraftBukkit start - update the client if the item is an infinite one
+                if (this.player.inventory.getItemInHand().count <= -1) {
+                    this.player.a(this.player.activeContainer);
+                }
+                // CraftBukkit end
             } else if (packet7useentity.c == 1) {
                 this.player.d(entity);
+                // CraftBukkit start - update the client if the item is an infinite one
+                if (this.player.inventory.getItemInHand().count <= -1) {
+                    this.player.a(this.player.activeContainer);
+                }
+                // CraftBukkit end
             }
         }
     }