update getRelationCountHash

Author: yurykozyrev

src/BaseRelation.php

@@ -130,9 +130,9 @@ public function getRelationQuery(
      *
      * @return string
      */
-    public function getRelationCountHash()
+    public function getRelationCountHash($incrementJoinCount = true)
     {
-        return 'nested_set_'.self::$selfJoinCount++;
+        return 'nested_set_'.($incrementJoinCount ? static::$selfJoinCount++ : static::$selfJoinCount);
     }
 
     /**
@@ -208,4 +208,4 @@ protected function matchForModel(Model $model, EloquentCollection $results)
 
         return $result;
     }
-}
+}