Handling $query->joinWith called inside of other $query->joinWith within Closure (called inside Closure). Ex.: ```php $query->joinWith( [ 'rel1' => function($query) { $query->joinWith( [ 'rel2' => function($query) { // ... } ] ); } ] ); ```
Fixes #4970: `joinWith()` called by a relation was ignored by `yii\db\ActiveQuery`