hasOne relation via() is not working as expected

[papppeter]

it creates new linking all the time, if i am populating it from a POST.

becouse of this: (line 279)
$relationModel = null; if (!empty($fks)) { $relationModel = $modelClass::findOne($fks); }

it creates a new instance
than (line 664)
if ($this->_oldRelationValue[$relationName] !== $owner->{$relationName}) {
will be false all the time. it links again, whenever it was a existing relation or not.

i am using php7.1