Prevent updating position column when is not dirty

Author: jakubdibala

src/PositionObserver.php

@@ -45,6 +45,11 @@ public function saving($model)
         if ($model->isPositionUpdateDisabled() === false) {
             // Get the position for current and old value
             $position = $model->getPosition();
+            
+            // Prevent modifying position column when updating and position columns has not changed
+            if ($model->exists === true && $model->isDirty($model->getPositionColumn()) === false) {
+                return;
+            }
 
             // Get the old position
             $oldPosition = $model->getOriginal($model->getPositionColumn());