Merge branch '6.x' into 7.x

Author: GrahamCampbell

Eloquent/Concerns/HasRelationships.php

@@ -256,7 +256,7 @@ public function morphTo($name = null, $type = null, $id = null, $ownerKey = null
  // If the type value is null it is probably safe to assume we're eager loading
  // the relationship. In this case we'll just pass in a dummy query where we
  // need to remove any eager loads that may already be defined on a model.
- return empty($class = $this->{$type})
+ return is_null($class = $this->{$type}) || $class === ''
  ? $this->morphEagerTo($name, $type, $id, $ownerKey)
  : $this->morphInstanceTo($class, $name, $type, $id, $ownerKey);
  }