Touch owners on save only if model is dirty (#14214)

src/Illuminate/Database/Eloquent/Model.php

@@ -1468,7 +1468,7 @@ public function save(array $options = [])
         // that is already in this database using the current IDs in this "where"
         // clause to only update this model. Otherwise, we'll just insert them.
         if ($this->exists) {
-            $saved = $this->performUpdate($query);
+            $saved = $this->isDirty() ? $this->performUpdate($query) : false;
         }
 
         // If the model is brand new, we'll insert it into our database and set the
@@ -1525,33 +1525,29 @@ protected function finishSave(array $options)
      */
     protected function performUpdate(Builder $query)
     {
-        $dirty = $this->getDirty();
-
-        if (count($dirty) > 0) {
-            // If the updating event returns false, we will cancel the update operation so
-            // developers can hook Validation systems into their models and cancel this
-            // operation if the model does not pass validation. Otherwise, we update.
-            if ($this->fireModelEvent('updating') === false) {
-                return false;
-            }
+        // If the updating event returns false, we will cancel the update operation so
+        // developers can hook Validation systems into their models and cancel this
+        // operation if the model does not pass validation. Otherwise, we update.
+        if ($this->fireModelEvent('updating') === false) {
+            return false;
+        }
 
-            // First we need to create a fresh query instance and touch the creation and
-            // update timestamp on the model which are maintained by us for developer
-            // convenience. Then we will just continue saving the model instances.
-            if ($this->timestamps) {
-                $this->updateTimestamps();
-            }
+        // First we need to create a fresh query instance and touch the creation and
+        // update timestamp on the model which are maintained by us for developer
+        // convenience. Then we will just continue saving the model instances.
+        if ($this->timestamps) {
+            $this->updateTimestamps();
+        }
 
-            // Once we have run the update operation, we will fire the "updated" event for
-            // this model instance. This will allow developers to hook into these after
-            // models are updated, giving them a chance to do any special processing.
-            $dirty = $this->getDirty();
+        // Once we have run the update operation, we will fire the "updated" event for
+        // this model instance. This will allow developers to hook into these after
+        // models are updated, giving them a chance to do any special processing.
+        $dirty = $this->getDirty();
 
-            if (count($dirty) > 0) {
-                $numRows = $this->setKeysForSaveQuery($query)->update($dirty);
+        if (count($dirty) > 0) {
+            $numRows = $this->setKeysForSaveQuery($query)->update($dirty);
 
-                $this->fireModelEvent('updated', false);
-            }
+            $this->fireModelEvent('updated', false);
         }
 
         return true;