Fixed qs.values() regression when used in subquery

1 files changed, 6 insertions, 1 deletions

diff --git a/django/db/models/sql/where.py b/django/db/models/sql/where.py
index ff3d1bdcfb..08f9d6c837 100644
--- a/django/db/models/sql/where.py
+++ b/django/db/models/sql/where.py
@@ -399,7 +399,12 @@ class SubqueryConstraint(object):
         if hasattr(query, 'values'):
             if query._db and connection.alias != query._db:
                 raise ValueError("Can't do subqueries with queries on different DBs.")
-            query = query.values(*self.targets).query
+            # Do not override already existing values.
+            if not hasattr(query, 'field_names'):
+                query = query.values(*self.targets)
+            else:
+                query = query._clone()
+            query = query.query
             query.clear_ordering(True)
 
         query_compiler = query.get_compiler(connection=connection)