Merge pull request #6023 from stof/add_property

Add missing definition of a property

src/Composer/Repository/ArtifactRepository.php

@@ -27,6 +27,7 @@ class ArtifactRepository extends ArrayRepository implements ConfigurableReposito
 
     protected $lookup;
     protected $repoConfig;
+    private $io;
 
     public function __construct(array $repoConfig, IOInterface $io)
     {