Fix proxy model Query.remove_inherited_models()

Fixed #18248 -- proxy models were added to included_inherited_models
in sql.query.Query. The variable is meant to be used for multitable
inheritance only. This mistake caused problems in situations where
proxy model's query was reused.

2 files changed, 10 insertions, 18 deletions

diff --git a/django/db/models/sql/compiler.py b/django/db/models/sql/compiler.py
index 69b508fe97..33949f5a71 100644
--- a/django/db/models/sql/compiler.py
+++ b/django/db/models/sql/compiler.py
@@ -261,12 +261,12 @@ class SQLCompiler(object):
         result = []
         if opts is None:
             opts = self.query.model._meta
+        # Skip all proxy to the root proxied model
+        opts = opts.concrete_model._meta
         qn = self.quote_name_unless_alias
         qn2 = self.connection.ops.quote_name
         aliases = set()
         only_load = self.deferred_to_columns()
-        # Skip all proxy to the root proxied model
-        proxied_model = opts.concrete_model
 
         if start_alias:
             seen = {None: start_alias}
@@ -277,12 +277,9 @@ class SQLCompiler(object):
                 try:
                     alias = seen[model]
                 except KeyError:
-                    if model is proxied_model:
-                        alias = start_alias
-                    else:
-                        link_field = opts.get_ancestor_link(model)
-                        alias = self.query.join((start_alias, model._meta.db_table,
-                                link_field.column, model._meta.pk.column))
+                    link_field = opts.get_ancestor_link(model)
+                    alias = self.query.join((start_alias, model._meta.db_table,
+                            link_field.column, model._meta.pk.column))
                     seen[model] = alias
             else:
                 # If we're starting from the base model of the queryset, the
diff --git a/django/db/models/sql/query.py b/django/db/models/sql/query.py
index efbc0c95a3..c91215fa9e 100644
--- a/django/db/models/sql/query.py
+++ b/django/db/models/sql/query.py
@@ -933,21 +933,16 @@ class Query(object):
         whereas column determination is a later part, and side-effect, of
         as_sql()).
         """
-        opts = self.model._meta
+        # Skip all proxy models
+        opts = self.model._meta.concrete_model._meta
         root_alias = self.tables[0]
         seen = {None: root_alias}
 
-        # Skip all proxy to the root proxied model
-        proxied_model = opts.concrete_model
-
         for field, model in opts.get_fields_with_model():
             if model not in seen:
-                if model is proxied_model:
-                    seen[model] = root_alias
-                else:
-                    link_field = opts.get_ancestor_link(model)
-                    seen[model] = self.join((root_alias, model._meta.db_table,
-                            link_field.column, model._meta.pk.column))
+                link_field = opts.get_ancestor_link(model)
+                seen[model] = self.join((root_alias, model._meta.db_table,
+                        link_field.column, model._meta.pk.column))
         self.included_inherited_models = seen
 
     def remove_inherited_models(self):