[5.2] firstOrCreate will not create new db rows when a model has a mu…

…tator (#14656)

* firstOrCreate will not create new db rows when a model has a mutator

* removed changes to firstOrCreate in Relationships

* fixed firstOrCreate mutating attribute twice

* replicated behavior of Builder before intial change. No mass assignment error thrown anymore

* fixed typo

* changed Builder edit to pass test. firstOrNew not creating null id when soft deleted user is called from instance

* white space issue

* addedAttributesToArray to declaration of mutatated Attributes

* use getAttributes instead of getAttributesArray

src/Illuminate/Database/Eloquent/Builder.php

@@ -233,7 +233,9 @@ public function findOrNew($id, $columns = ['*'])
      */
     public function firstOrNew(array $attributes)
     {
-        if (! is_null($instance = $this->where($attributes)->first())) {
+        $mutatedAttributes = $this->model->newInstance($attributes)->getAttributes();
+
+        if (! is_null($instance = $this->where($mutatedAttributes)->first())) {
             return $instance;
         }
 
@@ -248,7 +250,9 @@ public function firstOrNew(array $attributes)
      */
     public function firstOrCreate(array $attributes)
     {
-        if (! is_null($instance = $this->where($attributes)->first())) {
+        $mutatedAttributes = $this->model->newInstance($attributes)->getAttributes();
+
+        if (! is_null($instance = $this->where($mutatedAttributes)->first())) {
             return $instance;
         }