title: Update edge with upsert in OrientDB v3.0.3
body: <p>I am trying to implement this new upsert edge feature available with v3.0.3 but getting exception <code>com.orientechnologies.orient.core.exception.OCommandExecutionException: Error updating edge: 'out' is not a vertex.</code>
  I have created a class <code>Person</code> with <code>Name</code> field as unique index and <code>Friend</code> with field id as unique index. 
  Command issued : <code>UPDATE EDGE Friend SET in = (SELECT FROM Person WHERE Name = 'name1' ) , out = (SELECT FROM Person where Name = 'name2') , id = 'f1' UPSERT WHERE id = 'f1'</code>. Please let me know if I am using this correctly. Thanks!</p>