Fixed #20507 -- SubqueryConstraint alias relabeling

The SubqueryConstraint defined relabeled_clone(), but that was never
called. Instead there is now clone() and relabel_aliases() methods for
SubqueryConstraint.

A related problem was that SubqueryConstraint didn't correctly use
quote_name_unless_alias() of the outer query. This resulted in failures
when running under PostgreSQL.

2 files changed, 8 insertions, 6 deletions

diff --git a/django/db/models/sql/compiler.py b/django/db/models/sql/compiler.py
index bbe310c8c3..0180f6b6cc 100644
--- a/django/db/models/sql/compiler.py
+++ b/django/db/models/sql/compiler.py
@@ -786,8 +786,7 @@ class SQLCompiler(object):
             return list(result)
         return result
 
-    def as_subquery_condition(self, alias, columns):
-        qn = self.quote_name_unless_alias
+    def as_subquery_condition(self, alias, columns, qn):
         qn2 = self.connection.ops.quote_name
         if len(columns) == 1:
             sql, params = self.as_sql()
diff --git a/django/db/models/sql/where.py b/django/db/models/sql/where.py
index 08f9d6c837..2a342d417a 100644
--- a/django/db/models/sql/where.py
+++ b/django/db/models/sql/where.py
@@ -408,9 +408,12 @@ class SubqueryConstraint(object):
             query.clear_ordering(True)
 
         query_compiler = query.get_compiler(connection=connection)
-        return query_compiler.as_subquery_condition(self.alias, self.columns)
+        return query_compiler.as_subquery_condition(self.alias, self.columns, qn)
 
-    def relabeled_clone(self, relabels):
+    def relabel_aliases(self, change_map):
+        self.alias = change_map.get(self.alias, self.alias)
+
+    def clone(self):
         return self.__class__(
-            relabels.get(self.alias, self.alias),
-            self.columns, self.query_object)
+            self.alias, self.columns, self.targets,
+            self.query_object)