Removed useless hasattr in UpdateQuery._setup_query().

The if statement always evaluates to True.

django/db/models/sql/subqueries.py

@@ -93,7 +93,6 @@ class UpdateQuery(Query):
         """
         self.values = []
         self.related_ids = None
-        if not hasattr(self, 'related_updates'):
         self.related_updates = {}
 
     def clone(self, klass=None, **kwargs):