Added dispenser event.

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

@@ -46,16 +46,24 @@ public class TileEntityDispenser extends TileEntity implements IInventory {
         }
     }
 
-    public ItemStack b() {
+    // CraftBukkit start
+    public int findDispenseSlot() {
         int i = -1;
         int j = 1;
 
         for (int k = 0; k < this.items.length; ++k) {
-            if (this.items[k] != null && this.b.nextInt(j) == 0) {
+            if (this.items[k] != null && this.items[k].count != 0 && this.b.nextInt(j) == 0) {
                 i = k;
                 ++j;
             }
         }
+        
+        return i;
+    }
+
+    public ItemStack b() {
+        int i = findDispenseSlot();
+    // CraftBukkit end
 
         if (i >= 0) {
             return this.a(i, 1);